My Long List of Amplifiers and My Personal Review of Each!


So I have been in a long journey looking to find the best amplifiers for my martin logan montis. As you know, the match between an amplifier and speakers has to be a good "marriage" and needs to be blend exquisitely. Right now, I think I might have found the best sounding amplifier for martin logan. I have gone through approximately 34-36 amplifiers in the past 12 months. Some of these are:

Bryston ST, SST, SST2 series
NAD M25
PARASOUND HALO
PARASOUND CLASSIC
KRELL TAS
KRELL KAV 500
KRELL CHORUS
ROTEL RMB 1095
CLASSE CT 5300
CLASSE CA 2200
CLASSE CA 5200
MCINTOSH MC 205
CARY AUDIO CINEMA 7
OUTLAW AUDIO 755
LEXICON RX7
PASS LABS XA 30.8
BUTLER AUDIO 5150
ATI SIGNATURE SERIES 6005

With all that said, the amplifiers I mentioned above are the ones that in my opinion are worth mentioning. To make a long story short, there is NO 5 CHANNEL POWER AMP that sounds as good as a 3ch and 2ch amplifier combination. i have done both experiments and the truth is that YOU DO lose details and more channel separation,etc when you select a 5 channel power amplifier of any manufacturer.
My recollection of what each amp sounded like is as follows:

ATI SIGNATURE SERIES 6005 (great power and amazing soundstage. Very low noise floor, BUT this amplifiers NEEDS TO BE cranked up in order to fully enjoy it. If you like listening at low volume levels or somewhat moderate, you are wasting your time here. This amp won’t sound any different than many other brands out there at this volume. The bass is great, good highs although they are a bit bright for my taste)

NAD M25 (very smooth, powerful, but somewhat thin sounding as far as bass goes)
Bryston sst2(detailed, good soundstage, good power, but can be a little forward with certain speakers which could make them ear fatiguing at loud volumes)

Krell (fast sounding, nice bass attack, nice highs, but some detail does get lost with certain speakers)

rotel (good amp for the money, but too bright in my opinion)

cary audio (good sound overall, very musical, but it didn’t have enough oomph)

parasound halo (good detail, great bass, but it still holds back some background detail that i can hear in others)

lexicon (very laid back and smooth. huge power, but if you like more detail or crisper highs, this amp will disappoint you)

McIntosh mc205 (probably the worst multichannel amp given its price point. it was too thin sounding, had detail but lacked bass.

butler audio (good amplifier. very warm and smooth sweet sounding. i think for the money, this is a better amp than the parasound a51)

pass labs (very VERY musical with excellent bass control. You can listen to this for hours and hours without getting ear fatigue. however, it DOES NOT do well in home theater applications if all you have is a 2 channel set up for movies. The midrange gets somewhat "muddy" or very weak sounding that you find yourself trying to turn it up.

classe audio (best amplifier for multi channel applications. i simply COULDNT FIND a better multi channel amplifier PERIOD. IT has amazing smoothness, amazing power and good bass control although i would say krell has much better bass control)

Update: The reviews above were done in January 2015. Below is my newest update as of October 2016:



PS AUDIO BHK 300 MONOBLOCKS: Amazing amps. Tons of detail and really amazing midrange. the bass is amazing too, but the one thing i will say is that those of you with speakers efficiency of 87db and below you will not have all the "loudness" that you may want from time to time. These amps go into protection mode when using a speaker such as the Salon, but only at very loud levels. Maybe 97db and above. If you don’t listen to extreme crazy levels, these amps will please you in every way.
Plinius Odeon 7 channel amp: This is THE BEST multichannel amp i have ever owned. Far , but FAR SUPERIOR to any other multichannel amp i have owned. In my opinion it destroyed all of the multichannel amps i mentioned above and below. The Odeon is an amp that is in a different tier group and it is in a league of its own. Amazing bass, treble and it made my center channel sound more articulate than ever before. The voices where never scrambled with the action scenes. It just separated everything very nicely.
Theta Dreadnaught D: Good detailed amp. Looks very elegant, has a pleasant sound, but i found it a tad too bright for my taste. I thought it was also somewhat "thin" sounding lacking body to the music. could be that it is because it is class d?
Krell Duo 300: Good amp. Nice and detailed with enough power to handle most speakers out there. I found that it does have a very nice "3d" sound through my electrostatics. Nothing to fault here on this amp.
Mark Levinson 532H: Great 2 channel amp. Lots of detail, amazing midrange which is what Mark Levinson is known for. It sounds very holographic and will please those of you looking for more detail and a better midrange. As far as bass, it is there, but it is not going to give you the slam of a pass labs 350.5 or JC1s for example. It is great for those that appreciate classical music, instrumental, etc, but not those of you who love tons of deep bass. It is articulate sounding too
Krell 7200: Plenty of detail and enough power for most people. i found that my rear speakers contained more information after installed this amp. One thing that i hated is that you must use xlr cables with this amp or else you lose most of its sound performance when using RCA’s.
Krell 402e: Great amp. Very powerful and will handle any speaker you wish. Power is incredible and with great detail. That said, i didn’t get all the bass that most reviewers mentioned. I thought it was "ok" in regards to bass. It was there, but it didn’t slam me to my listening chair.
Bryston 4B3: Good amp with a complete sound. I think this amp is more laid back than the SST2 version. I think those of you who found the SST2 version of this amp a little too forward with your speakers will definitely benefit from this amp’s warmth. Bryston has gone towards the "warm" side in my opinion with their new SST3 series. As always, they are built like tanks. I wouldn’t call this amp tube-like, but rather closer to what the classe audio delta 2 series sound like which is on the warm side of things.
Parasound JC1s: Good powerful amps. Amazing low end punch (far superior bass than the 402e). This amp is the amp that i consider complete from top to bottom in regards to sound. Nothing is lacking other than perhaps a nicer chassis. Parasound needs to rework their external appearance when they introduce new amps. This amp would sell much more if it had a revised external appearance because the sound is a great bang for the money. It made my 800 Nautilus scream and slam. Again, amazing low end punch.
Simaudio W7: Good detailed amp. This amp reminds me a lot of the Mark Levinson 532h. Great detail and very articulate. I think this amp will go well with bookshelves that are ported in order to compensate for what it lacks when it comes to the bass. That doesn’t mean it has no bass, but when it is no Parasound JC1 either.
Pass labs 350.5: Wow, where do i begin? maybe my first time around with the xa30.8 wasn’t as special as it was with this monster 350.5. It is just SPECTACULAR sounding with my electrostatics. The bass was THE BEST BASS i have ever heard from ANY amp period. The only amp that comes close would be the jC1s. It made me check my settings to make sure the bass was not boosted and kept making my jaw drop each time i heard it. It totally destroyed the krell 402e in every regard. The krell sounded too "flat" when compared to this amp. This amp had amazing mirange with great detail up top. In my opinion, this amp is the best bang for the money. i loved this amp so much that i ended up buying the amp that follows below.
Pass labs 250.8: What can i say here. This is THE BEST STEREO AMP i have ever heard. This amp destroys all the amps i have listed above today to include the pass labs 350.5. It is a refined 350.5 amp. It has more 3d sound which is something the 350.5 lacked. It has a level of detail that i really have never experienced before and the bass was amazing as well. I really thought it was the most complete power amplifier i have ever heard HANDS DOWN. To me, this is a benchmark of an amplifier. This is the amp that others should be judged by. NOTHING is lacking and right now it is the #1 amplifier that i have ever owned.
My current amps are Mcintosh MC601s: i decided to give these 601s a try and they don’t disappoint. They have great detail, HUGE soundstage, MASSIVE power and great midrange/highs. The bass is great, but it is no pass labs 250.8 or 350.5. As far as looks, these are the best looking amps i have ever owned. No contest there. i gotta be honest with you all, i never bought mcintosh monos before because i wasn’t really "wowed" by the mc452, but it could have been also because at that time i was using a processor as a preamp which i no longer do. Today, i own the Mcintosh C1100 2 chassis tube preamp which sounds unbelievable. All the amps i just described above have been amps that i auditioned with the C1100 as a preamp. The MC601s sound great without a doubt, but i will say that if you are looking for THE BEST sound for the money, these would not be it. However, Mcintosh remains UNMATCHED when it comes to looks and also resale value. Every other amp above depreciates much faster than Mcintosh.

That said, my future purchase (when i can find a steal of a deal) will be the Pass labs 350.8. I am tempted to make a preliminary statement which is that i feel this amp could be THE BEST stereo amp under 30k dollars. Again, i will be able to say more and confirm once i own it. I hope this update can help you all in your buying decisions!


whitecamaross

Showing 50 responses by 4425

not to be difficult but I wonder how these amps would rate in a blind test..I find that "very" good amps have small differences when all other variables are removed. also after the new wears off you wonder what was wrong with the prior great amp.
IMHO the big differences heard in any new high end component has more to do with the initial hyper focus on the sound which diminishes over time bringing you right back to 'why did I sell uber good amp x for uber good amp y' ?
I've been fortunate enough to have had Dartzeel, JRDG and Agostino over the last 5 years or so and know that I should have kept the Dartzeel (first in line) bc all three are great amps that produce darn near flawless sound with differences I couldn't possibly describe today. It's the quest for new that makes the hobby fun and expensive..Just my observation after many years. Just take a look at all the great amps for sale in audiogon. absolutely no reason to sell except to try something new.

BTW using a Krell Chorus multichannel amp and look forward to every time I turn it on. It's just another great high end amp.

i know it’s not of the scale of the neoliths but i’ve been told by a source i trust that the sanders electrostatic is among the very best of that genre.
 personally if i had the room the top of the line magnepan would certainly be fun to set up properly. 
what a contrast. i find the luxman pair to be anything but ‘muffled’. it’s very transparent and detailed. very
After perusing this thread pretty quickly I would like to make a few comments.
1. No audition of Jeff Rowland 625 S2 or S1. First Jeff is an american audio icon and contrary to a comment made about rowland research resale it's perhaps the best in holding its value. Try to find a 625 used or new at a good price. Not out there. Built like no other. 
2. Unless i missed it I can't imagine not auditioning a D'Agostino amp. Another american icon. Try a master classic or a used momentum stereo. built like rowland.
3 You really must audition Dartzeel. Either the CTH8550 integrated or legendary NHB 108b. Correct matching powerwise required here. Not made for low impedances below 4ohms. This gear is up in audio thin air as is Rowland and D'Agostino.
4. finally the pass 250.8 i auditioned did not light my fire. a good solid state amp but not distinguished in my humble opinion. and lord is pass available used. they are discounted so much upfront that a resell is competing w a dealer. i don't like that.
Sorry for the long winded post and of course it only represents my opinion.

I liked the pass. Just not as much as Agostino Rowland and Dartzeel.. The only thing I had to compare to the Pass at the same time was the Krell Chorus 5200 in two channel mode. I thought they were comparable and both good sounding Class A solid state units. Solid state is so good now I would never go tube amp. Dartzeel  pre so good I wouldn't consider tubes either. But big money unless you can find a version 1 used. They fly out the door on AGON.
ARC once described tubes as being like light bulbs that can pop at any time. I crank sometimes and would be unrelaxed knowing that. No need to take a chance with my speakers...Just my two cents. 
What what a crazy world audio is. I feel that the Revel Salon 2 to be very high on any list of great speakers. In all truthfulness if the sound heard from them is not inspiring something is wrong elsewhere. Period.  
Under any scenario the Salons are great speakers. However it is true that better is the enemy of good.
Haven't read all the responses so if it's been mentioned my apologies. I think that you should see if you can get a Dartzeel NHB 108 to try in your system. By any definition it is considered one of the most musical amps ever made. Swiss build quality by a master designer. The Dartzeel's always resell when you can find one. If interested contact Jonathan Tinn at Blue Light Audio. He might have a demo and has always been great to me. Last word. In my humble opinion most people use far less juice than they think. Always remember that it takes twice the power to increase sound output by 3db. Too long winded I am but I think you'll love the Krell too. This series was great stuff. 
envy is an ugly thing. it’s quite evident when one uses the term “rich people”.
it’s the new mantra for those that feel that life is unfair bc we are not all on the same economic playing field.
no more politics. let the man continue. it’s a very interesting to hear unbiased impressions of different gear. FWIW
have to ask as i’m just a part time observer of this thread. am i correct that people are judging sound quality of cables and speakers via computer audio systems? 
also i very much like the poster’s non biased opinions. they are hard to find. this assumes that his suppliers are not either giving hot deals or expecting him to plug their products. i personally have no problem with that other than it would inject some bias into the situation. he seems straight up to me and obviously thick skinned to have to listen to so much BS. like mine....
i think it’s a fine idea for fun and quite a lot of work. i just wanted to be sure i understood. that said, you guys hearing differences in cables using this manner are way better audiophiles than me. as another example i think that someone actually dissed DAW’s based on this method. no one has any idea how they sound until you hear them in your own living room.
i think, without knowledge, that what you’re really judging is your computer speakers. imo
My experience is that a judgement made before at least a few days have gone by might not be the correct one. FWIW
i agree w previous poster. my own personal experience w the salons was that they are a state of the art speaker in their price range and above.
universally praised for very good reason. if the salons sound muffled one has a very dark system.
last note. the salons are one of jeff rowland’s demo speakers which i heard at his ofc in Co. I was totally blown away. overwhelmed actually
BTW I don’t own a pair. Just a big fan
The controversy that continues concerning Wilson perplexes me. Maybe it’s older generations that were the issue. I’ve owned a LOT of high end speakers over my 61 years. The last pair was Salon 2’s which I enjoyed very much except for a small vocal edge that was probably room related. 
That said I purchased a pair of Wilson Yvette’s and am absolutely mesmerized with their musicality. Forward? Beats me as I’ve never felt a need to pick them apart. Geez they are satisfying. I’m not a big Wilson fan other than I love my pair.
FWIW
Just an opinion here but I personally can’t very well judge the nuances of component and cable changes in less than a few weeks. Aural memory always in play. I really don’t mean to be critical but what you’re doing doesn’t sound like fun. Obviously you have a strong following which is great but your hearing is vastly superior to mine if you can keep up with all the permutations involved. You’re playing at a level where it’s all good. I wish you the best and hope that you are having fun. I’d be close to nuts for sure.
BTW you’ll like the Rowland. Amazing low key designer. Built like jewelry.
Another unsolicited recommendation is to audition with a familiar system a ML 523 pre. As a 61 year old obsessed audiophile I’ve never heard anything as musical except the latest generation Dartzeel. I was truly surprised as hell. 
Well in my personal experience once my system is disassembled or altered it takes a few days to return to its normal self. Not my imagination but certainly can’t explain it. IMO of course
Late to the thread. Maybe you’ve addressed this but back in the thread you were going to buy a ML 52. Did it ever get compared to the Luxman pre? I’m pretty high on ML latest preamps. The Luxman unit is new to me. Thanks if you have an opinion. 
WC. don’t mean to be critical but your comment that you were ‘told’ that the Constellation amps were better than the Agostino is not compelling. If you can judge sound quality by what someone tells you then no need to audition. 
Wilson’s sound awesome with Agostino too. Breathtaking. 
Are you off the Luxman C-900u pre now? Earlier in the thread I thought it was a favorite. The Ref 10 leagues better? 
I’ve been in and out of this thread but don’t remember Agostino amps being under consideration. Is this bc of lack of dealer aggressive pricing? Even the entry level  Momentum S250 deserves a shot I would think. What gives?
Guido: you mention soulution which i’m positive is great gear. i keep seeing used listings on agon with almost staggering discounts. i’ve always wondered why this is. what’s the deal? 
I know that practical considerations have no place here but I can’t help myself. When contemplating a Ref 6 vs the Lux I would not disregard two issues:
1. The 6550 tubes in the Ref 6 power supply offer potential significant damage should one blow. More risk than a Ref amp losing a tube. This is straight from ARC.
2. All ARC preamps are really not designed to drive subwoofers except possibly REL. Very few matches might work. 

The Lux has many wonderful attributes with no downside. Blind fold test them and see if there is superiority in the Ref 6 worth taking on some liabilities. Just a thought. No agenda here I assure you.

For what it’s worth my D’Agostino S250 driving Wilson Yvette’s has the slightest of meter movement when playing at a reasonable level. This seems to indicate as I’ve always believed that we need far less watts than we think. I have a pretty large room and occasionally juice it up with very slightly more meter movement. Trust me, it’s got mojo and damn beautiful to behold as it should be given the price. I don’t have any idea how he gets such a heavy transformer in this unit. It’s 100lbs of dead wgt in a smallish pkg.
Last thing. Yvette’s spec’d at 86db and 4ohms.
Ok guys I don’t want to be a grinch but so be it.
This “beats” it verbiage bugs me. It’s not a boxing match but rather determining what sounds best to the listener. I don’t think any SS amp will “beat” the Agostino but something else might sound better to the listener given his or her preferences. We are all different in what we want the final tonal balance to be etc. It could be that a less expensive component fills the preferences better than a more expensive component. Strictly an individual thing.
One thing is for absolute certain. Until you’ve hooked all the gear up, cooked it and listened for a month or more no one can get the real measure. It simply takes time. Then add one new variable and do it again. Hard to be patient but it’s the correct procedure. I’m not good at it but it’s the way it is. Changing a speaker puts you back at ground zero. FWIW
Not part of the thread but have to chime in. IMO if the Agostino integrated doesn’t sound great and drive the speakers well then the speakers have issues. I don’t think anyone disputes that Agostino amps play in the top 10% of all SS amps. The audiophile insecurity that somehow mating a preamp and amp in one chassis is a compromise is simply mental. I know as I’ve thought the same thing at times but realize it’s just in my head. You can try other SS amps for fun but they won’t change the situation in a meaningful way except to perhaps diminish the overall sound quality. You’ve got a great piece! I wish I had one.
Another comment or two from a guy that has done some of what wc is doing. switching out gear without establishing constants.
The correct way in my humble opinion is to find  a base point. In this case I would suggest to only use the Agostino integrated with the speakers and NO other change for at least a month. Any system sounds best untouched after it’s set up and cooking. Just leave it alone. 
Get a true handle on the sound as set up then ONLY work on speaker placement. Once you’re in rarified air as wc is the adjustment of the speaker will have the greatest impact. many in this thread have said so. Changing an amp like the DAG just isn’t going to fundamentally change things. If the DAG has 200w into 8ohms I expect that into 2ohms it has a ton of mojo. Never forget that you must double the amp’s output for an additional 3db of perceived volume increase. 
Repeating myself I would just leave everything alone and enjoy the music the system is making for no less than a month. wc has great gear in hand and should be in no rush to add another variable into his system. Constantly changing components is frustrating and confusing. 
finally(too long winded) forget the concept that bc it’s an integrated amp its 200w is somehow different than a free standing 200w amp. Totally wrong and illogical. It just ain’t so. If in a month the sound is unsatisfactory it’s the speakers or room interaction but it’s not the DAG amp. I believe this 100%. As always FWIW.
just wondering, given your ability to locate great deals on great equipment, what about Agostino?
Tough or not so much? Thanks for your thoughts. 
ditto to previous post. 
a couple of unsolicited thoughts from a 40+ year audio veteran.
1. never forget that when a new item is installed into a system the listener is hyper focused almost insuring that differences will be heard. my experience is that no judgement can be made in less than a week or more. what’s exciting on day one will most likely not be so exciting the following week. maybe yes maybe no.
2. the tone controls on the Dag integrated and Luxman pre have more power to positively alter the sound than any other component or wire. Consider the “sparkle” issue that has been brought forth in this thread. It was said that the Dag integrated lacked sparkle with apparently a speaker that is on the darker side of neutral. Naturally a neutral amp on said speaker will sound dark. It’s supposed to. An amp that had “sparkle” on this same speaker would then be bright on a neutral speaker. All is not lost however as a judiciously applied treble boost of 1-2db will add plenty of “sparkle” from the Dag when and if needed. Ditto for the Luxman pre. This is infinitely better that trying to match components within the bright/dark continuum. 
Once an audiophile geek such as myself gets over the bias against tone controls a whole new world of better sound can open up imo. 
i think that you’d be wise to put the momentum integrated back in with a top end hurricane or similar cord finding a way to make it blind. that’s a report i’d love to hear. the concept of ‘sparkle’ intrigues me. high end well designed amps should only have ‘sparkle’ if on the recording. An emphasis on the high end will produce too much ‘sparkle’ on bright recordings. Neutral is always better. The beauty of the momentum is that you can add 1-2db to the treble allowing you to dial in ‘sparkle’ as desired. fwiw i don’t own one.

As an infrequent poster I know I shouldn’t chime in but regardless I find most of this thread to be utterly pointless. With over 40 years of buying and selling high end gear, much too frequently, I can say with certainty that switching gear at the rate of the OP results in zero true conclusions about anything. Simply audiophile delusion by no means limited to OP who is obviously a thoughtful and nice person. 
If budget was not a consideration why wouldn’t you experience the Momentum 400’s? I would expect power and finess in a gorgeous pkg imo.  My S250 wants for nothing. It’s awesome as well it should be.
And if price was no object the Dartzeel NHB 468 would be my buy and forget piece. Actually so would the M400’s.. 
Step it up!

i’m sure i missed it in the thread but why aren’t  big arc monos in the mix with the ref10? at this level of buying and selling it can’t be the tube cost plus arc can be bought well discounted and holds its value well especially if bought correctly. 
the pass fans aren’t going to be happy w your comments. 
i have a C-900u driving wilson speakers with an ARC Ref 75se. It’s awesome. however i think so highly of this preamp that i ordered an M-900u. the preamp is refined and colorless with great texture. i would not call it warm but rather neutral AND rich. it really is extraordinary. i actually can’t imagine a good amp that wouldn’t work well with it. if the combo doesn’t sound very good it’s the amp. i think using a less than neutral preamp is not the way to build a system. fwiw i’ve used the C-900u with rowland and agostino to great effect. i also preferred this preamp to the ML 523, the latest dartzeel and the rowland corus. imo
casually following this thread may mean i’ve missed something so my comments may not have much meaning.,
with cable swapping now in full gear i have to assume a permanent amp and preamp are now selected. otherwise adding these cable variables just mucks it up. if i was actually contemplating spending odin kind of money i would think long and hard about spending the funds on an even higher level of gear, if possible.
you have to have great cables at this level but the rig comes first.
if one can chase cables at the odin level then said person can afford to keep ARC’s best mono blocks in tubes. the tube amp will make a much greater impact than any high end cable and provide a much more exciting listening experience. i do it with a great solid state preamp that has the features i want into a tube amp. it’s fundamentally different than lateral solid state amp choices. that said i’m still all SS at a high level but when i insert an ARC amp its a new sound altogether and frankly a more exciting one.
regardless of the type of preamp used the amp is the last link before the speaker. 
i think ss first to tube last makes great sense, at least to me. FWIW
This is one interesting but funky thread. How do you go from the big ML to Paradigm? Geez. No Wilson. No big Magico(i think). No big Maggie’s and on and on. and you use odin. flipping gear around is great fun if you can afford to play the game but old school bias would not lead me to Paradigm. no i’ve not heard them and don’t question that they may sound really good but fun is playing with ML, Wilson, Magnepan, Magico etc.
A truly unsolicited opinion so my apologies if I’ve offended anyone.  
Maggie 20.7. That’s fun.
magnepan 20.7 or 30.7 would be awesome to try. d.a.w the same. you might find a stick.
wont get a good deal but won’t have trouble reselling. this would entertain you. surely you’re not going to make changes to your system to optimize for the paradigm? 
mike knows his stuff. i trust him a lot. 
Hate to be a grinch but the op was initially searching for great amplifiers listening to some very good ones one at a time. it would be nice if the thread could recenter toward the initial goal. great amps!
A very few A+ sonic gems . May have been mentioned already. Mainstream recordings that won’t leave you wishing for vinyl. Trust me.
Love over Gold.   Dire straits 
Brothers in arms.  Dire straits
Document.  Rem
Honky Chateau Elton John 
Madman Across the Water.  Elton john
One more car one more driver. Eric Clapton
Live at Pompeii. David Gilmour
The Dance. Fleetwood Mac
Broken Arrow. Neil Young
Live at Bass Hall. Lindsey Buckingham
Late Mozart piano concertos.  Any that are on channel classic label 
All the pretty horses soundtrack 

fwiw i have the luxman C900u and M900u and would never call them warm and boring. they are very transparent with all the ‘sparkle’ that’s on the recording. they don’t make poor recordings sound better and awesome recordings are mesmerizing. upon further reflection i can say that they have the best high frequencies that i’ve yet encountered. very refined and extended.
personally i’d like to hear your thoughts on ML 536 monos. 400/800 wpc. they are doing great things these days. as an example the 523 preamp is really really good. i preferred it to the dartzeel preamp latest version which is superb in its own right. 
I think you will in the end be happy with either the Luxman pre with the mono amps or the new ARC monos should you end up preferring tubes. 
i believe i’ve read that the arc amp sounds the best from the 8ohm taps regardless of speaker impedance. difference is said to be transforming. fwiw