Pass XA Monoblock Amps

I know there have been many threads on these amps and the different levels of power with each set. To those who owned the Pass XA60.5 and went to the Pass XA100.5 monoblocks, did you feel that the change made a big difference in your system or was it not that noticeable whether played at low to mid level volume levels or high volume. I currently own the Pass 60.5 and am contemplating the Pass 100.5. Some people have suggested that it would take a move to the Pass XA160.5 for it to really make a difference but that would unfortunately be out of my price range. The room is 12 by 24 and the speaker load is 2 ten inch seas woofers, 2 seven inch mids, and the tweeter. They are 4 ohm with a sensitivity of 91 but a big speaker. Any thoughts from Pass owners of these amps would be appreciated. The other direction i can go would be to upgrade my Pre-amp from the Rowland Capri but my initial thought was that the Pass amp change would be more of an upgrade. Thanks for your thoughts.
I haven't owned any of the Pass monoblocks but do have an INT-30A. I think that for the money it would cost to upgrade to the XA 100.5s you could improve the sound of your system much more by getting a new preamp, and be able to change the sound in a variety of different ways.

Now to attract a little vitriol, I once read an interview with Nelson Pass where he said the amps of the XA.5 series all sound the same to him, the higher powered ones just have more power. I wish I could find the interview but I can't. This is not meant to question or aggravate anyone who has moved up the XA.5 power ladder. I'm sure that you have better ears than me and you really do hear whatever improvement you hear.

I moved up from the XA100.5 to the XA160.5. The former were great amps, but when I replaced my speakers to ones having a very difficult load, I needed more current and power. The XA100.5 shifted into classAB during demanding passages. They also sounded just a bit constricted with the new speakers.

After I inserted the XA160.5, everything sounded freer. The stage opened up a bit, dynamics improved, and surprisingly, there was better low level detail and nuance. The sound was a bit more round and palpable.

I was told by Mark at RENO something like you get a bit more of everything as you move up to the bigger amps. I don't know if I would notice such a difference with more efficient speakers. I suspect the improvements I heard are because my new speakers require the bigger amps.

Your speakers are much more efficient at 91dB than mine are at 86dB. You also have a larger room than mine, so it's kind of tough to offer advice about needing the bigger amp. Have you ever seen you needles move on the meter? If you have, you may want more power. I have always preferred the largest Pass amp I've had within the series, both Aleph and XA.5.

Regarding the preamp question, I have not heard the Rowland Capri. My XP-20 works extremely well with my XA.5 amps, IMO. You could contact Mark at RENO or a local Pass dealer and ask. I would want to demo the XA100.5 against the XA60.5 and also the XP-10, or XP-20 against the Capri. There are some great deals now on Pass preamps.

The needles on the amps move when i get to high volume levels . Thanks for your thoughts as well as Tom's thoughts. I know its hard to describe but I wonder what the Pass pre-amps bring to the match with the Pass amps as I have only heard my amps with the Capri. What i had read in the past about Pass Pre amps was that they tended to sound a bit on the thin side and were on the detailed side of neutral. It sounds like you are quite happy with sound you are getting from the XP-20.
It would seem that the Pass XA60.5 driving 91 db efficient speakers in a 12x 24 room should be more than enough power. What are your listening levels in db?
Hi Charles,

I don't know what my listening levels are in db. I know that the volume control on my Capri pre-amp goes from 0-100. When I get in the zone of 65-75, the bias meters start moving and i can tell that the amp is going out of class a to a/b. When this happens depends on the recording.
I also own XA60.5's and recently replaced my X-1 pre with the XP-10 and feel the XP-10 gives a little more of everything. I've never heard the Capri, so can't comment on that.

I've also considered moving up to the XA100.5's but in my room size of 10X18 the meters rarely move. I'm running Martin Logan CLS IIz with a 86 dB sensitivity but they are crossed over at 88 Hz to my sub, so my power requirements are less.
I agree with "some people". Get the XA160.5s. Particularly if you like orchestral music. It's not just about loudness, but playing complex and large pieces without strain. I also have 91 dB sensitivity speakers into 4 ohms, and I can still get the meter to bounce a little when all 100 musicians are playing at the same time.

The only downside to having too much power with these amps is the heat. The big ones sound beautiful as well. I still can't think of an amp I'd rather have. Except for maybe the Pass XS300...
I wish i could afford the XA160.5's but i can't. It is a 2.25 db increase from the Pass XA60.5 to the PassXA100.5. How much that will affect my headroom as well as the capacity to play loud without going into class a/b is probably unknown until i have them in my system as the room plays a part also.
Pettyfeversk, something does`nt seem right here. According to Nelson Pass the XA.5 series is "pure Class A" and is an ultra high current design(factor of 5x compared to the previous series current output capabilities) his words.It has a very stout power supply(obviously).
Your speaker is`nt a difficult load. At 4 ohms your amp will have plenty of current reserve(per design objective). Unless you want ear damaging volume your amp should really be fine for any type of music.

I`d speak with someone at Pass Labs before I`d follow the advice of some here to move up to a larger amplifier. Have you done that yet?
Hi Charles,

Thanks for responding. The XA.5 series has a very strong class A power supply but if you have the volume up to a high level, you reach a point where they transition from pure class A to classA/B. That happens with all the amps in the XA series and definitely happens to me with my speakers which can take a good amount of power. You can see the bias need move as you go up the volume level and they move to AB.
A point that might be relevant is that speaker sensitivity is often defined with respect to 2.83 volts, rather than 1 watt. For an 8 ohm speaker that would make no difference, since 2.83 volts into 8 ohms corresponds to 1 watt. But 2.83 volts into 4 ohms corresponds to 2 watts, so if the 91db figure of your 4 ohm speakers is defined with respect to 2.83 volts, they would be 88db/1W/1m speakers, not 91db/1W/1m.

I did a quick Google search, but couldn't determine how the 91db is defined.

Beautiful system and setup, btw.

-- Al
Bingo, Almarg!
I have recently moved from Tyler's Woodmere 2 to the new-style full-sized Woodmeres, and I am getting to know the speakers pretty well now. Tyler had told me that the Woodmeres are 90db, calculated theoretically based upon the crossover/driver combination. Their load drops to just above 2 ohms at worst case, according to Tyler. I suspect that if they were measured in a lab, the 88db figure would be about right. These larger speakers require a pretty good bit of power (and I think current also) to make them sing. They sound very nice and relaxed at low volumes, but they do like the juice.
Al, I wonder how those bloody Cardas cables contribute to the overall sound from the perspective you mentioned?
Rocket science, anyone?
Inna, I have no particular familiarity with the Cardas GR's, but from a specification standpoint, at least, I don't see any concerns. Resistance and inductance are extremely low. Capacitance is a little bit on the high side, but I would feel certain that it is not anywhere close to being high enough to cause sonic issues with a Pass amp (conceivably it might be if used with an amp that uses lots of feedback and has extremely wide bandwidth; the Pass amps do not have either of those characteristics).

Rtilden, thanks for providing the good info.

-- Al

Thanks for your thoughts as they are most appreciated. It is more of a push to drive these Woodmere loudspeakers related to the 4 ohm load. Whether they are actually 88 or 91 sensitivity, the more power they get, the better I believe they will perform. I have always like the Cardas Golden Reference cables. They are not only wiring my system , but I believe (but could be wrong) that they are used by Rowland in their products and Running Springs Power Conditioners also use them.