Pass Labs:What to expect fm XA60.5 to XA100.5


Hi Guys,

Some of you may know that I have some buzz/hum issue in one of newly received XA60.5 mono blocks. The dealer diagnosed the problem and determined the transformer needs replacing. Since the XA60.5 is only few days old so I am given the chance to get a replacement set or I could top up the price difference to get the X350.5 or XA100.5s when my dealer gets their stocks in the next 3-4 weeks time.

Kudos to Pass Labs and the dealer's service for all the patience and after sales services...certainly very much appreciated and glad I go for Pass Labs.

As such, I have 3-4 weeks to listen to the current XA60.5 in my system while waiting for the stocks to arrive and make the final decision on the swap/upgrade.
elmerpoh
Some information:
Speaker : Von Schweikert Unifield II on 60cm stands
CD player : Bel Canto CD-2 as transport
DAC : Bel Canto 3.5VB
Preamp : Using the DAC pre amp at the moment

Room : Dedicated Audio room with no other furniture
Around 4meters by 3.5 meters sized room with speaker playing down the long side of the wall. Acoustically treated with absorbers at the sidewall for first reflection.

The front wall is treated with 2D diffuser and at the back of the Speaker with absorbers to control some of the bass.

Music I usually listen to:

10% Rock
30% Jazz
30% Vocals
30% Concerto (Classical music, Instrumental and Movie Soundtracks)

I normally listen at volume of between 70db to 80db max.

I was using the Bel Canto Ref 1000 MK 1 before the Pass Labs XA60.5.

The Pass Labs experience certainly is a very pleasant one. The leaner high and mids of the Class D certainly is now replaced with the liquid and lush high/mid that I appreciate and enjoy a lot. Not mentioning the musicality, natural, neutrality, transparency, PRAT (Pace Rhythm Attack Timing) and bigger soundstage also went up a few notches with the XA60.5. The usual Jazz and Vocals CDs I listened to previously on the Bel Canto Ref 1000s became so much more enjoyable. I could listen to these genres for hours and hours without knowing how fast the time passed and also without any fatigue. I really like the qualities of Class A amps.

However something seems to be missing when I listen to Rock and Concertos (Classical music, instrumental and Movie Soundtracks). It seems that the dynamism, speed and attack are not as fast paced and exciting as the Class D, other wise the others qualities are much superior in the Pass Labs.

The questions I have in mind which hope anyone who have experiences with the XA60.5, XA100.5, X350.5 and Bel Canto Ref 1000s(or any Class D amps) could comment/advise.

1) Any benefits in my listening experience(sonics, dynamism, low transients,etc) if I upgrade the XA60.5 to XA100.5?
Considering unchanged everything else (i.e.listening room, volume and music etc) as mentioned above.

2) I was told XA100.5 could be the amp I could be living with for a long long time even if I planned to upgrade to the VSA VR-4 SR MK3 or VR5 Anni in next 3-5 years if I get a bigger room for pure Audio usage.

3) Would the XA100.5 or the X350.5 be the missing puzzle of what I felt missing with the XA60.5 vs. Class D?

4) Would XA100.5 match the speed,imaging,instrument separations,soundstage and explosive feels vs. the X350.5 when listening to Rock and Concerto (Classical music, Instrumental and Movie Soundtracks)?

I do understand any comments/advise could be solely based on individual views and maybe subjective, however any inputs would greatly be very much appreciated.

Thank you all in advance.

Cheers



This is a little off topic, but I too am currently listening to a Class D integrated, a Jeff Rowland Concerto. It runs very cool and sounds very good to my ears. However I'm waiting on the arrival of my Maggie 1.7's and while the Rowland will certainly supply the muscle needed to drive the Maggie's, I've read how wonderful the Pass XA amps sound with them.

My room & listening preferences match yours. I'm wondering if your Pass XA 60.5's throw off a large amount of heat in your relatively small room? I live in Texas with VERY hot summers, but have a room with good air conditioning.

Good luck on you ultimate decision. From everything I've read about the Pass amps, I think a pair of XA 100.5's would be the way to go.
Hi Kenl,

Yes,The reviews are pretty much true, the Pass Labs XA indeed have magical mids and highs.. You need to hear them...

Regarding heat from the XAs, no issue since you have air conditioning in your listening room.

When I listen to few hours of music with the XA60.5 without air conditioning, they only run slightly hot to touch(I.e. could still touch the heat fins for about 8-10 secs).

Cheers
With your speakers I would not expect much of a difference going from the XA-60.5 to the 100.5, it just doesn't seem like power (a fairly marginal difference here) is the issue, not with your speakers and your room. Did you ask Pass Labs?
Are you running balanced or single ended from the Bel Canto DAC to the XA-60.5?

The Bel Canto DAC outputs 2.5Vrms single ended and 5.5Vrms balanced. If you're running single ended it's *possible* dynamics are being affected, and you might try running balanced instead.

At the volume levels you normally listen, there will be no discernible difference between the XA-60.5 and XA-100.5, IMO. At 98dB peaks, you're only using 8 watts of power.
Though I did not say it before, I should have added that IMHO the XA60.5 will sound as good, if not better than the XA100.5 IF it provides enough power to drive your speakers to the volume levels you want, and in the case of your speakers, that would seem to be the case. All things being equal, my opinion is that the same basic circuit design sounds better in a lower watt configuration than higher watt because it is a simpler device at lower watts. My general rule is buy as many watts as you need, but no more than you need.
I went from the XA100.5 to the XA160.5. My speakers are a very demanding load and I thought I would need more power/current. I first demoed my speakers with the XA30.5 and they sounded a bit restricted during loud classical passages. My XA100.5 was better so I considered the XA160.5. I called Kent at Pass and he said I would get a bit more of everything. He was right. Better dynamics, larger soundstage, more effortlessness, better air, better control of bass. All this in a small room at moderate volume 75-90 dB. Music just became more involving. The improvement was not huge, but better in every way. For me, it was definitely worth the upgrade cost.

I am not familiar with your speakers and have not heard the XA60.5. I suggest you contact Pass Labs and describe your situation. I also have not heard the X350.5, but if you like the pure Class A sound and the XA100.5 is enough for you, it might just be the ticket.
Does the meter on the XA60.5 bump around alot? If it moves on more than an occasion, go with the bigger amps.

Your description of the sound of Rock and Concertos with the XA60.5 does sound like a potential power issue.
Elmerpoh, how far from the speakers do you sit? Is this the distance from which you measure your listening volume?

If so, measure again from your listening position, and then move to 1 meter from one of the speakers, measure this volume and report it here. Try to measure a loud music peak. Be sure to point your decibel meter at one speaker or the other...not down the center.
Hi Guys,

Thank you for all the inputs.


Pubul57
With your speakers I would not expect much of a difference going from the XA-60.5 to the 100.5, it just doesn't seem like power (a fairly marginal difference here) is the issue, not with your speakers and your room. Did you ask Pass Labs?

07-12-10: Pubul57
Though I did not say it before, I should have added that IMHO the XA60.5 will sound as good, if not better than the XA100.5 IF it provides enough power to drive your speakers to the volume levels you want, and in the case of your speakers, that would seem to be the case. All things being equal, my opinion is that the same basic circuit design sounds better in a lower watt configuration than higher watt because it is a simpler device at lower watts. My general rule is buy as many watts as you need, but no more than you need.

Hi Paubl,
As my speakers are in 4 ohms, the difference in terms of Pure Class A wattages powering are 120watts@4ohms for XA60.5 and 200watts@4ohms for the XA100.5, in addition the XA100.5 has a damping factor of 200 instead of 150 in the XA60.5 and X350.5. Not too sure if increase of 50units damping factor will be a big improvement effect to the speaker I am using. The Unifield 2s are 91db/1m @ 4ohms min. Pass Labs advised if I want an amp able to run most if not all speakers in a mid to large room and to keep it for a long long time to come, it would be the XA100.5.
I was always told all speakers like wattages, the higher the better.


07-12-10: Tvad
Are you running balanced or single ended from the Bel Canto DAC to the XA-60.5?

The Bel Canto DAC outputs 2.5Vrms single ended and 5.5Vrms balanced. If you're running single ended it's *possible* dynamics are being affected, and you might try running balanced instead.
At the volume levels you normally listen, there will be no discernible difference between the XA-60.5 and XA-100.5, IMO. At 98dB peaks, you're only using 8 watts of power.

Hi Tvad,

I am connecting using balanced outputs from the Bel Canto DAC. I am thinking if the higher wattage(120w vs 200w @ 4ohms),higher damping factor(150 vs 200)higher output Voltage(32 vs 41) and higher output Amps(20 vs. 28) will bridge the gap on dynamism, speed/explosive transient between the XA.5 and Class Ds.


07-12-10: Peterayer
I went from the XA100.5 to the XA160.5. My speakers are a very demanding load and I thought I would need more power/current. I first demoed my speakers with the XA30.5 and they sounded a bit restricted during loud classical passages. My XA100.5 was better so I considered the XA160.5. I called Kent at Pass and he said I would get a bit more of everything. He was right. Better dynamics, larger soundstage, more effortlessness, better air, better control of bass. All this in a small room at moderate volume 75-90 dB. Music just became more involving. The improvement was not huge, but better in every way. For me, it was definitely worth the upgrade cost.

I am not familiar with your speakers and have not heard the XA60.5. I suggest you contact Pass Labs and describe your situation. I also have not heard the X350.5, but if you like the pure Class A sound and the XA100.5 is enough for you, it might just be the ticket.

Hi Peterayer,
I have enjoyed your review of the XA100.5 very much think its hard to improve the experience. The higher level models of the XA.5 must be really something.Cannot imagine what the XA200.5 could provide. For me XA100.5 is the furthest I could stretch. Not sure if the benefits of X350.5 on dynamism, speed/explosive transient,high Class AB 700watts @4ohm will make me forget the smooth liquid mid/high of the XA.5 Class A power. No best of 2 worlds as one would say I guess.


07-12-10: Rtn1
Does the meter on the XA60.5 bump around alot? If it moves on more than an occasion, go with the bigger amps.

Your description of the sound of Rock and Concertos with the XA60.5 does sound like a potential power issue.

Hi Rtn1,
The meter does bump/swing slightly when i am playing rock and concertos at about 80db volume, but it does not pass the 12 o'clock mark.


Elmerpoh, how far from the speakers do you sit? Is this the distance from which you measure your listening volume?

If so, measure again from your listening position, and then move to 1 meter from one of the speakers, measure this volume and report it here. Try to measure a loud music peak. Be sure to point your decibel meter at one speaker or the other...not down the center.

Hi Tvad,

I am sitting at the sweet spot location which is about 2.2meters away from the left and right speaker.
I am only taking the listening volume from the volume level shown on my Bel Canto DAC acting as pre amp.

At the moment i do not have a SPL meter, will try to find one to do some measurements.

Cheers
I am only taking the listening volume from the volume level shown on my Bel Canto DAC acting as pre amp.

Elmerpoh (Threads | Answers | This Thread)
I don't believe that's measuring decibels.

Take some measurements with a decibel meter and report back. You'll receive significantly better advice when we know how loudly you actually listen.

Please also try to measure the decibel level at a distance of 1 meter from your left or right speaker during high volume peaks.
Elmerpoh,

Given your 91dB and 4 ohm min impedance and the fact that you listen fairly close to your speakers, I would think that the XA100.5 would be plenty of power and the X350.5 might be overkill without as much Class A magic.

I would enjoy the XA60.5 until your dealer gets the new amps in. Then, just audition each one in your own system and decide which you like better. I think it will be the XA100.5 over the X350.5. Remember, they need to be on for a few hundred hours to break in, at least mine did. Then, just enjoy the pure, glorious sound.
Elmerpoh, disregard the suggestion to measure your listening volume with a decibel meter. It will be an exercise for no reason. It's fairly easy to discern that you intend to purchase XA-100.5 amplifiers whether or not you really need them to drive your speakers sufficiently.

This past time is as much about buying the most one can afford than it is about buying anything based on actual need.
Tvad,

Could you please elaborate on your last post? You seem to suggest that all one needs to do is calculate SPL in a room and match the amp to speakers on paper and all will be fine.

The XA100.5 looks as though it has plenty of power to drive my Mini II's. Dealers even said as much. I have a small room and don't listen too loudly. The bias needle moved only slightly and not too often. However, switching to the bigger XA160.5 gave me better sound. I still have the same sized room, don't listen any louder, the needle almost never moves now, but dynamics, scale, staging and control of the lower frequencies are all better. The music is more involving and enjoyable.

Sure it costs more, uses more electricity and generates more heat, but the results are well worth the upgrade cost to me.

Now, the sonic signature of the X.5 is surely different from that of the XA.5 and the OP should hear the difference before committing.
"I was always told all speakers like wattages, the higher the better."

I do think all speakers need enough watts to perform well, the quantity varies with the speaker, room, music, and loudenss preferences. I also know folks like VTL will suggest you need 1,000 watts to really allow speakers to blossom. That being said, I think there is always (almost always?)a loss in quality as watts go up for a specific circuit design, but that can be a fair tradeoff if your speakers need the power, and some speakers do need alot of power, or more importantly current to drive low and dipping impedances. I think that on speakers like mine (Merlin VSM)the XA30.5 (which I did own)will sound better than the XA100.5. But I have know doubt the XA100.5 will sound alot better driving Thiel or B&Ws - they need the power and the current. So the question isn't really which is the better amp, but which is the best amp/speaker combo, and I'm not sure why the XA100 would drive your speakers any better than the XA60s (but they might).

07-13-10: Pubul57
"I was always told all speakers like wattages, the higher the better."

I do think all speakers need enough watts to perform well, the quantity varies with the speaker, room, music, and loudenss preferences. I also know folks like VTL will suggest you need 1,000 watts to really allow speakers to blossom. That being said, I think there is always (almost always?)a loss in quality as watts go up for a specific circuit design, but that can be a fair tradeoff if your speakers need the power, and some speakers do need alot of power, or more importantly current to drive low and dipping impedances. I think that on speakers like mine (Merlin VSM)the XA30.5 (which I did own)will sound better than the XA100.5. But I have know doubt the XA100.5 will sound alot better driving Thiel or B&Ws - they need the power and the current. So the question isn't really which is the better amp, but which is the best amp/speaker combo, and I'm not sure why the XA100 would drive your speakers any better than the XA60s (but they might).

Hi Pubul,

My main dilemma is: Given everything the same(i.e. speaker,room,listening volume, genre of music i listen to, source,etc) except upgrading from XA60.5 to bigger wattage power of XA100.5(higher damping factor of 200,higher output voltage and current too) or X350.5(higher output voltage and current), Should I expect improvement on dynamism, speed/explosive transient to draw closer the gap between Class A or A/B with the Class D that I previously owned.

From what I read from Peterayer's reply, it seem higher wattage model of the XA.5 models does indeed have better overall presentation of sound in the same given speaker(though I am not using the Mini II).

Wonder will there be actually a plateau of overall presentation on sonics quality where a given speaker no longer will/can improve further when using a higher model amplifier of the same brand.

Cheers
Some Pass X.5 owners will have to pipe in here, but for some reason I think the X.5 series might very well be more dynamic than the XA.5 series, but that you will lose some midrange liquidity moving from XA to X - not sure if that is a matter of power differences or circuit design differences. Class A is generally "smoother" and that might (not sure here) be we you notice as reduced "explosiveness" and "transient speed". As far as I can tell, the damping factor differences should not account for much (especially with your speakers).
If I understand your situation correctly you will have the opportunity to listen to both amplifiers. You will have a better chance of making a good decision if you listen to each one without expectations of what they will or won't do. Listening without preconceptions is a good thing.
I own a XA100.5 with WP Sasha. Before buying tha XA100.5, I compared it with a XA60.5 that is a very great amp. The difference between both is the bass are far better articulate,with XA100.5. I compared the XA100.5 with the X350.5, and I prefered the XA60 because it's much more musical, you feel more involved into the music. So if you do not need the power of the XA100, go to XA60.5.
^jp
I would expect the XA-100.5 to be "better" than the XA60.5 with the WP Sasha, that amp/speaker combo is better suited to the needs of the WP. But, as Onhwy61 points out, listening is worth 10,000 threads on the topic (now if you can only get rid of preconceptions during the listening - hard to do sometimes).

07-13-10: Onhwy61
If I understand your situation correctly you will have the opportunity to listen to both amplifiers. You will have a better chance of making a good decision if you listen to each one without expectations of what they will or won't do. Listening without preconceptions is a good thing.

07-13-10: Pubul57
I would expect the XA-100.5 to be "better" than the XA60.5 with the WP Sasha, that amp/speaker combo is better suited to the needs of the WP. But, as Onhwy61 points out, listening is worth 10,000 threads on the topic (now if you can only get rid of preconceptions during the listening - hard to do sometimes).

Hi Onhwy/Pubul,

My local dealer unfortunately does not have the XA100.5 or X350.5 in demo to listen/audit. I was even unable to hear XA60.5 before commiting. However prior putting my cash down, I was able to audit the X260.5(mono blocks) and XA30.5 on Sonus Faber Auditor M as the dealer is also a Sonus dealer. I like the mids and highs on the XA.5 but the XA30.5 lows was abit loose and not as articulate sounding as the X260.5. Thinking the XA60.5 monoblocks should better that concern and XA60.5 in my room indeed does better than what i heard on XA30.5 at the dealer's premises.

If not issue in one of the XA60.5's transformer,I would not be given the chance to change/upgrade models. Maybe sometime chance of choices are not that good afterall.


07-13-10: Jpspock
I own a XA100.5 with WP Sasha. Before buying tha XA100.5, I compared it with a XA60.5 that is a very great amp. The difference between both is the bass are far better articulate,with XA100.5. I compared the XA100.5 with the X350.5, and I prefered the XA60 because it's much more musical, you feel more involved into the music. So if you do not need the power of the XA100, go to XA60.5.

Hi Jpspock,
For my info, did you manage to try the XA100.5 and XA60.5 on the same WP Sasha? Was the comparison on the XA60.5 and X350.5 on the same speakers as well? Fully agree that the XA.5 has more magical high and mids than the X.5, that was what i felt when i hear the X260.5 and XA30.5 both on the Sonus Faber Auditor M.
the latest TAS said the Sasha is not an easy speaker to drive, leading me to believe the higher power option is preferable.

in fact, RH said it was the hardest to drive speaker in the Wilson line. ymmv.
Yup, I would think XA100.5 or higher, but those 100s are conervatively rated, might do the trick with the Sashas, but it does seem to be one of those speakers like some Thiels and B&W were the more power the better - they need it.
Hi Elmeroth,

I listened the XA60 and 100.5 the same day on the same Sasha. I compared the X350.5 with 250.5, 600.5 on Sophia2 and the on WP8. One thing is very important too : the preamp. I have compared the XP10 and XP20 with XA100.5 and X600.5 and XP20 is much better : wider and deeper image, deeper and articulate bass, magnificient midrange. So when you will listen to those gears, don't forget the impact of the preamp, because it can change everything.
The plot thickens...
Elmerpoh,

I must have misunderstood you. I thought from your original post that the dealer is getting new stock (both the X350.5 and the XA100.5) in the next 3-4 weeks. I assumed you would simply be able to listen and compare them to your XA60.5 at the shop or better in your system. Now it seems that these will not be available to you to demo/audition in your own system. Is that the purpose of this thread? The dealer will have these for you to purchase, but you will not be able to listen to each ahead of time? That is the only way to really know for yourself.

I agree with Jpspock. The pre amp makes a big difference and the Pass units sound great with the Pass amps. Have you considered getting a preamp and just repairing the XA60.5 instead of upgrading the amp? I would ask Pass or the dealer if this makes more sense.

Peter
Peter, is it your feeling also that the XA60s is more than enouch power for his speakers? It certainly seems that way.
A little late to the discussion here. I use XA-30.5 to drive my speakers with 91dB/w sensitivity and presents 4 Ohm load under 1KHz. I listen to music fairly loud, louder than most of my friends. Even that loud level is only around 80dB at the listening position - average. The musical peaks can reach 90dB and up. As to how the dB figures translate to the real world, at 80dB it is somewhat difficult to carry out conversation without significantly raising the voice. At 90dB you would be shouting to each other and barely hear them. Most my friends listen at 65-75dB on average. I assume that's the same for vast majority of audiophiles.

What that means is most people don't _need_ that much power in reality, unless the speakers are extremely inefficient or difficult to drive. But it's like owning a car. Most people don't need 500HP engine but we all want to.

Nelson Pass wrote about what it really means for an amp to transition from class A bias to class A/B bias. That's when the needle starts to move for Pass amps. The needle moving past the stationary position is not an indicator of the amp running out of capacity. The maximum power for XA-.5 amps are published elsewhere, and they are significantly higher than what the model number suggests. The maximum power is of course delivered in class A/B mode. Then the question is will someone be able to discern the "quality" of power delivered in class A mode vs class A/B mode of the same amp. That's a good question, but it's of no concern for me any more. The needle on the face plate jumping up and down was maybe a little bit entertaining in the beginning, for example during the canon fire of Tchaikovsky's 1812. But I came to the conclusion that my amp has plenty of power for me, and nothing good will come out with worrying about the class A vs A/B currents and needle movements. That way you tend to enjoy the music more.
Pubul57,

I think the XA60.5 should have enough power for Elmerpoh to enjoy his system. I've tried (unsuccessfully I guess) to make three points in this thread.

1) I have always benefitted from more power with my Pass amps. Enough power to drive a given speaker to certain SPL is one thing, for the speaker to sound it's best is often another. For me, the XA160.5 sounds considerably better driving my Mini II's (87dB, 4 ohm) than did my XA100.5. Elmerpoh may prefer the sound of the XA100.5 to the XA60.5 even if it seems like the added power is not needed.

2) Elmerpoh may benefit more from a Pass pre amp with his existing XA60.5 than with the XA100.5 and using his DAC directly for roughly the same money.

3) The only way to be really sure which amp he will prefer is to listen to the X350.5 and the XA100.5 in his own system if this is possible. The dealer may not allow this. It is unclear.

I have always bought the biggest Class A Pass amp I could afford at the time, and with my speakers, Eggleston and Magico, the sound has benefitted.
I bought a pair of XA160.5's based on a combination of auditioning an XA30.5, advice from Aerial about 20T's power requirements, reading about Peterayer's experience, and this commentary from an email to Pass, which might help a little. You might want to email them about your specific circumstances.

I am very happy with the XA160.5's by the way. You should know that the XA100.5's will heat your room about 50% more than the XA60.5's - I would estimate 1,400 btu/hr for the pair. The extra ~500 btu's are unlikely to matter much if you have ample air conditioning - it's like having two more people sitting in the room.

>>
>> The XA30.5 is very much a good indication of the XA line both for
>> spectral balance and detail. As you move to the larger pieces you get
>> "more" of what the XA-30.5 already is.
>>
>> The exception if there is such a thing would be the XA60.5's. They are
>> more dynamic and powerful as one would expect, but their character is
>> very slighlty warmer than the XA30.5 and XA100.5 at low to moderate
>> listening levels
>>
>> The XA100.5's are very similar in character to the XA30.5 but by virtue
>> of their ability to drive any load we can imagine, pretty much set the
>> standard for dynamic contrast and focus of image.

>> Best
>> Kent English / North American Sales
>> Pass Laboratories
>>
The comment from Pass regarding the characteristic of the XA-60.5 to be warmer than the XA-30.5 at low to moderate listening levels was not true in my system: Silverline Sonata III/Lamm L2 Reference. In fact, the XA-30.5 was warmer than the XA-60.5.

07-14-10: Peterayer
Elmerpoh,

I must have misunderstood you. I thought from your original post that the dealer is getting new stock (both the X350.5 and the XA100.5) in the next 3-4 weeks. I assumed you would simply be able to listen and compare them to your XA60.5 at the shop or better in your system. Now it seems that these will not be available to you to demo/audition in your own system. Is that the purpose of this thread? The dealer will have these for you to purchase, but you will not be able to listen to each ahead of time? That is the only way to really know for yourself.

I agree with Jpspock. The pre amp makes a big difference and the Pass units sound great with the Pass amps. Have you considered getting a preamp and just repairing the XA60.5 instead of upgrading the amp? I would ask Pass or the dealer if this makes more sense.

Peter

1) I have always benefitted from more power with my Pass amps. Enough power to drive a given speaker to certain SPL is one thing, for the speaker to sound it's best is often another. For me, the XA160.5 sounds considerably better driving my Mini II's (87dB, 4 ohm) than did my XA100.5. Elmerpoh may prefer the sound of the XA100.5 to the XA60.5 even if it seems like the added power is not needed.

2) Elmerpoh may benefit more from a Pass pre amp with his existing XA60.5 than with the XA100.5 and using his DAC directly for roughly the same money.

3) The only way to be really sure which amp he will prefer is to listen to the X350.5 and the XA100.5 in his own system if this is possible. The dealer may not allow this. It is unclear.

I have always bought the biggest Class A Pass amp I could afford at the time, and with my speakers, Eggleston and Magico, the sound has benefitted.

Hi Peter,
I am unable to have any head to head hearing of the XA60.5,XA100.5 and X350.5 as my dealer does not allow unsold open boxes.
I do agree that pre amp can makes a some difference of the sound amplified out to the speakers.
Was told there are 2 school of thoughts on pre amp;
1)If I do not have more than 1 source, maybe better to connect the DAC directly to the power amp since the DAC has decent pre amp qualities.
2)Adding a pre amp to give the finishing touch of sound before its being amplified by the power amp to the speakers.

Point 2 actually make me think whether using a decent Tube Pre with the X350.5 makes the sonic qualities compare with the XA.5 series(especially lush/bodied/liquid mids and highs).

I agree with the point 1 & 2 you made. Does agree that 120w @ 4ohms is sufficient for my speakers in my room, just trying to establish whehther what improvement I can expect by going from XA60.5 to XA100.5 with all else being unchange.
Point 3 is something which I am trying to get views from someone which has heard them before since i am unable to do.

So far I can gather the following choice given unable to hear them side by side:

1) Get a replacement set or repair the XA60.5(which i am not happy with the bottom end sonics), maybe add a pre to the XA60.5 to seek better sonics on the lows.
2)Swap for the X350.5 and match with a decent tube preamp to touch up the mids/highs.
3)Swap the XA60.5 with XA100.5 and get a Pass pre amp at later stage.

Cheers
A couple thought to consider, since you have a few weeks before you need to make a decision.

If the amps are brand new, they're maybe still breaking in. The sound will be a little more vivid after they are fully broken in. Make sure they ARE broken in ASAP so you're really hearing them properly.

Also, your speaker/listening positions, dacron stuffing, etc. are still probably what you found worked best with your prior amp. You might be able to get what you want for free just by going through that process again.

In the same vein, try a few other cables if you can during the next couple weeks, since it sounds like you're already pretty close to what you want, and you might feel compelled to do this anyway once you've got the amplifier thing settled.
If I were you I would contact Pass Labs directly and talk to them about your dealer. I think it's ridiculous that you cannot audition these amplifiers. You're a proven customer. Does your dealer really expect people, particularly people who have shown that they are real buyers, to buy $10k plus equipment without seeing and hearing the product? It's even more outrageous that you're being so terribly disrespected after receiving a defective product. There's no way you should tolerate being treated so poorly!

Alternatively, for the price of the items you're considering the cost of a plane ticket to a dealer who has the items in stock and allows potential buyers to audition is not all that significant.
07-15-10: Onhwy61
If I were you I would contact Pass Labs directly and talk to them about your dealer. I think it's ridiculous that you cannot audition these amplifiers.

Alternatively, for the price of the items you're considering the cost of a plane ticket to a dealer who has the items in stock and allows potential buyers to audition is not all that significant.
An excellent point, and an equally excellent alternative.
If the amp is going back to Pass for repair anyway, perhaps you could just contact Mark @ Reno to set up an audition of the XA100.5 and the X350.5. I'm sure Pass and Reno could work out an accommodation as customer service is a top priority for them.

Scratch that, I just noticed you are in Singapore. The dealer should let you audition. If not, contact Pass and find another dealer. Should should hear the difference for yourself.
Excellent and very valid points guys,
I will need to have a good talk with my dealer.

Hope this unfolds well...

Thank you all for the inputs.

Cheers
Good luck!
Elmerpoh,

What did you decide to do? Can you update us? Thanks.
Hi Peter,

Thanks for checking back.

Can you believe I am still waiting for the stock of Pass labs amps to arrive my local distributor. It's been close to 3 months in about a weeks time.
Would love to give you some views of the jump from the xa60.5 to xa100.5 which I intends to do.

Still waiting anxiously.... The dealer says the shipment is on the water and I got that since 1 month ago and still avail.

Will definitely update my views of the sound when I have the xa100.5 settled my small audio room.

Cheers
Hey Guys,

Just an update, finally my long wait for the XA100.5 ends 2 days ago.

Have it delivered, setup and running in my room.
Played for first 3 hours and already noticed the benefits of having more headroom even if its not required.

Cannot wait to run them in another 100hrs before giving further views against what i had previously experienced with the XA60.5.

Cheers
Congratulations!! Great amps with almost any speaker.
I am curious as to which amp you chose. Assuming that your speakers have a 90dB efficiency rating. You would only need about 1 Watt/channel to drive them to around 80dB at 3 meters so the XA60.5 should provide all the power that you need. See the following link for power calculations:
(www.myhometheater.homestead.com/splcalculator.html)

The advantage to Class A is that there is no distortion due to cross over from A to AB operation so operating at low power output levels won't be an issue. A couple of advantages that the XA60.5 has over the XA100.5 is the 33% lower up front cost and the 33% lower power consumption (200W versus 300W).
Elmerpoh,
You never gave your impressions of the new amps. Do you still have them and how do they compare with the XA60.5?
My speakers are 90 db efficiency. My amplifier provides 400+ watts into 4 ohms. I use every one of those watts, every day. And not just for a couple seconds.
I owned the 350.5 and the 250.5 at the same time, and for me in my system the 250.5 was the winner. It simply had better synergy equally from top to bottom. The 350.5 was leaning more to the upper frquencies and not as balanced as the 250.5

My friend also had the 250.5 and bought the xa 60's. We pretty much have the same system, and to me the xa 60 were to liniar not as much weight and body as the 250.5. Some what like the 350.5.

I here the xa 100's are more full bodied like the 250.5
My current amp is an Aleph 60W/ch. It has plenty of power for my Avantgarde Duo's. If I upgrade then I will probably go with the XA60.5's.
7p62mm: "A couple of advantages that the XA60.5 has over the XA100.5 is the 33% lower up front cost and the 33% lower power consumption (200W versus 300W)."

And in my experience, lower power versions of the same circuit generally sound better than those requiring more complex output stages for the additional power - IF you have sufficient power. With 90db speakers, 60 watts 8 ohm should be more than enough, unless you really like the idea of premature hearing loss or the ability to make you neighbors want to move or sue you.
Hi Guys,

Apologies for the late update, was tied up and seldom log into the site.

Yes, I've upgraded to the XA100.5 and used the same VSA Unifield 2s on the 100.5 and 60.5.

What I felt from different amps on the same speaker, the 100.5 sure have more headroom, and sounds less congested when playing heavy tracks(classical and live rock concert). The beautiful mids are similar to the 60.5 but do feel there's slightly more definition and resolution with the 100.5 on the mids and highs hence the soundstage sounds more focus. Some increase in width and height on the soundstage too.

Overall, the music picture portrayed by the 100.5 is towards a denser and complete sound if compared with the 60.5.

The 60.5 is a great amp, but with higher Pure Class A watts using the same design does better it and it should being a higher cost model.

If one can stretch, go for the 100.5. I agree from some of the comments I read and heard, the 100.5 is the sweet spot model among the XA.5 series in Pass Labs.

Now as they say, nothing is perfect. Coming to the down side of 100.5, I am always craving for even more resolution, more speed and a tighter and more defined low ends from them especially when I am listening for live music concerts on classical or rock. Believe this is the design and characteristic of Pass Labs sounding slightly layback with benefit of a more beautiful mids and highs.

I have since moved on and am very happy what I can achieve with the Soulutions.

Cheers
"always craving for even more resolution, more speed and a tighter and more defined low ends...design and characteristic of Pass Labs sounding slightly layback"

Interesting, because that is not what I experience. Not doubting what you hear or your musical preferences because you've done the comparison. But, I hear natural and flowing music. Pace, detail, staging, and lower end are just right.

Solution seems to make fine amps, too.