Higher-End Class A/B vs. Class A Integrateds

I’ve been thinking about downsizing from separates to an integrated amp. I’ve noticed that some companies have both class A and class A/B amps that are both pretty expensive such as Luxman for example. Hegel seems to be well received and they’re not true class A as far as I know.

I was kind of under the impression that class A was better than class A/B due to lower distortion yet again, there are some well reviewed class A/B amps that are as pricey as some class A amps.

To be clear, it’s really not the price I’m concerned about. It’s the fact that some integrated amps $5000 and up are still only Class AB.

How do these higher priced class AB amps sound in comparison to true class A amps?


If you are near a Pass Labs dealer you could always compare a class A/B directly to Class A. Pass Labs drop out of pure A at their rated output to A/B and keep going producing more power. You would have a chance to see say what an X line can do, what an XA/Int can do in class A then up the power requirements to get everything into A/B. 

If they have another high biased A amp available then you have more to directly compare to.

I've got an MSB S-200 integrated amp; their design has, per the manual, "pure class A stage to increase the voltage signal, and class A-B stage with no voltage gain to increase the current supplied.". This amp was in the $10,000 range when it was new (I bought a demo), and it sounds awesome; the only part of my hi-fi system I've had no interest in upgrading over the past 10 years. 

I appreciate the replies. I have heard a friend’s Class A PBN amp (not integrated). I liked the sound I heard but yes, it would nice to do a direct comparison..

I don’t know how much power it puts out in Class A and I asked him and he doesn’t know.

It’s a huge, heavy amp with a single meter that I think indicates current not db’s.

He has money and just buys stuff. LOL!

I’m looking to spend no more than $5000 preferably used.

I bought my Sonus Faber speakers at Audio Concepts in Dallas.  They sell Luxman, D'Augostino, Boulder, McIntosh, Naim and Moon by Simaudio.

I'll have to try and see if they can set me up with a direct comparison using my speakers.


I would caution you on the pure Class A Luxman integrateds (20W & 30W) driving a difficult load/ low sensitivity speaker. They will produce very little bass to the extent that you would think a component is broken. I tried to power a pair of KEF Ref 1Metas with a 590 AXII, those speakers ate the integrated up. Their M10X is a different story though and produced prodigous bass. 


Thanks for the advice.  I may want to upgrade my speakers sometime and I would like an amp that can drive my future speakers without having to upgrade the amp ... again.

The Sugden class A integrated amps sound wonderful and are reasonably priced for their sound quality, especially when bought preowned. I downsized from LTA separates (a lot more expensive), and in my system I didn’t lose anything, very happy (running the amp into Revival Audio Atalante 3 standmounts, excellent).

I was kind of under the impression that class A was better than class A/B due to lower distortion yet again, there are some well reviewed class A/B amps that are as pricey as some class A amps.


There are some megabuck Class A amps I would never trade my A/B Luxman integrated for. The theory is that Class A amplifiers have less distortion right at the zero crossing point, but in absolute distortion terms it is not always the case that Class A has less distortion, it just doesn’t suffer from one particular challenge. I find the peculiarities of an amp to be much more important than the class. Also, I can’t really imagine living with a large class A amplifier due to the power waste.

There are even some Class D designs I like a lot more than some famous Class As.

Are you just looking for the lowest distortion?  You cannot determine sound quality by class alone.  We build pure class A mono blocks and hybrid power amplifiers.  It comes down to design implementation and the quality of parts.  If you want a good power amp for the price, try out the BEL power amps. Even the early models have a beautiful sound.

Happy Listening.

 The class matter less that the design details which matter less than the room controls over the amp/speakers coupling ...


I own the Luxman AXII - love the sound, luxman says it’s 30 watts pure class A, but reviews have measured that it’s 30 watts pure class A and after that A-B up to 90 watts. I don’t know who is right, but it sounds great and has enough power for my Harbeth 30.2s, 

It does get hot, though not as bad as tubes. I would say that if you’re looking at new inefficient speakers, you may want more power, although I have not found that to be a problem with the Harbeths. 

I doubt there is anything for $5k used for what you want to accomplish. Just because you are planning to downsize doesn't mean that you are ready to downgrade. 

As others mentioned, I wouldn't pay much attention to whether it is class A or class AB to begin with. It should sound right with your current and future speakers.

+1 piebaldpython

I have owned a Pass Labs X250.8  I have only 87 db efficient speakers playing in quite a large room. I play at moderate volumes all kinds of music.  I HAVE NEVER seen the amp leave Class A on the meter....just saying...

Unison Research have some beefy Class A units ... 


I believe The Music Room is a dealer ....



There are very good class AB integrated amps , Boulder , Gryphons new 333,

accuphase, Luxman ,  if youwant class A Accuphase,and Luxman make them too

up to 100 watts into 4 hours , but they get pretty warm and suck up a ton on electricity, it’s like holding your foot down 24-7 to the gas petal . I owned a pass labs  . What are your speakers ,and  their sensitivity ,at what ohms is most important .

Hmmmm people seem to forget SET Tube Amps are Class A by nature. A 845 will get you 20watts so dont over look that option also.



As several have mentioned, listen and borrow if you can. I've heard two Class D amps that I thought had heart and soul, and would definitely audition if/when I consider combining to an integrated; Gato and Aavik. The Gato is around $5,000 and unfortunately the Aavik is well north of that. I have never heard them in my system, but would like the chance at some point

Class A will usually have a warmer sound signature.  My Hegel H390 has a somewhat warm yet nicely articulated sound.  I like it paired with my Maggie 3.7's.  And yes, class A runs much hotter and takes more juice, even when it's not making music.

Rather than focus on pure class A, you might want to look at A/B amps that are are biased to deliver more class A wattage before switching to A/B operation. Some vendors publish these numbers, others do not. Coda is one example. If you don’t play your music loud, or have sensitive speakers, you may not need a lot.  More important however is how the amp sounds to you and how well it plays with your speakers. 

You might consider a used Krell K300i integrated.   The first watts are Class A then the rest are class A/B.   I don’t recall the actual cutover, but it’s pretty high.   I own one and love it.   Smooth, warm (not bloomy), extended highs, and massive controlled bass.   I’m very satisfied with mine.   Used you can find them for about $5k.

Happy hunting!


I once owned a Krell KSA Pre w/phono.  It was a great pre and one piece of equipment I wish I never parted with.

The K300i sounds very intriguing.  The only thing that turns me off is the fact that it has no volume knob.  That could be something I could get used to.


That's why I've been questioning the whole Class A thing vs. Class AB.  I had noticed integrated amps at close to $10,000 that were Class AB.  I thought, once you got into that price range they would surly be pure Class A.  

I found out that that's not the case and that there are obviously very rich sounding class AB out there to consider.


Right! I see a lot of the Hegel's up for sale some around that price or lower and listeners seem to love the Hegel sound.


My speakers are Sonus Faber Lumina III's.  These will probably be upgraded some time in the future but I'm happy with them for now.

The specs are:  

  • Sensitivity: 89 dB SPL (2.83V/1m)
  • Nominal Impedance: 4 ohm

My listening room is 13'L x 12'W x 8' H

My listening position is about 7' from the front of the speakers

I do listen loud at times.

The Boulder 866 is outstanding and well worth an audition. Good luck in your search! 

The gold note dealer - Rutherford audio - is having a close out sale on their entire line. The PA1175 MK2 sounds good as well as the IS-1000 integrated. Don’t pay the listed price, haggle it down. 



I agree that a proper integrated or preamp should have a volume knob.   The Krell 300i has buttons instead (not as good as a knob) and it has a great remote.   I just use the remote, so it works for me.


I mostly use my remote as well.  Sometimes playing vinyl, I like to lower the volume  with the knob when I get up to change or flip a record but I don't think it should be a deal breaker.

Kinda seems like this jumped right into the weeds about amp design without getting some critical bigger-picture info.  You’ve got a long list of equipment on your system page so what are you using now, what improvements would you like to achieve (if any), and what sound characteristics are most important to you?  That’s really the bottom line more than whether a given amp is Class A or A/B, at least IMHO.

Why do people conflate the heat of an amp to it's "sound signature?" Tube people do it all the time and it seems some class A people do too. Utterly baffling.


I am presently using the Classe CP-50 pre with the McCormack DNA 0.5 DE. Was trying to keep things cool in the Texas summer.

I may put the tube power amp in soon for a change of pace.

Anyhow, in my original post, I mentioned that I’m looking at moving away from separates and looking to get a nice sounding integrated. The only reason is that I heard a friend’s system where he’s using a PBN power amp (don’t know the model) and he claims it’s class A. I doubt that it’s all class A but I’ve no idea how many watts are class A. I did like the sound though. It seemed more pleasing to my ears. Smooth like going from a well scotch to an 18 yr. single malt. Effortless. And vocals on some recording made the hair on the back of my neck stand up.

That’s why I’m curious as to whether I need to go Class A for that sound or will some Class AB designs fit the bill.

My room is fairly small and I sit fairly close to the speakers.

I listen to mostly Rock and Jazz so yes, I tend to listen loud a lot.

Post removed 

Ok, as far as my friend’s PBN power amp. I asked him and he couldn’t find out much other than it’s the PBN Olympia Mini ( he thinks). I think he’s a little fried from his days of playing in bands in the 80’s and 90’s. From what I’ve been able to find, it is not a class A amp. It’s class AB. It weighs close to 100lbs.

It did sound good to me but was that because I was convinced it was class A at the time or was it that it has more power than what I’ve been using? IDK.

You folks gave me much more to consider as far as an integrated amps go. I feel now, that I can find one that does not have to be Class A and hopefully will be just as satisfying.

+ 1 for the Krell 300i, it’s class A up to 90 watts which I would guess you will rarely if ever eclipse.  I had the opportunity to demo the Krell, I owned a Coda CSiB, Primaluna Evo 400 integrated and at the same time demo’d the Krell 300xd Duo Amp (not an integrated unit).  I landed on buying the 300xd Duo but that was purely because I wanted the flexibility of separates.  The Krell XD line is incredible in my opinion, the drive, control is amazing but it has a touch of warmth, tubiness that is amazing as well.  The 300i integrated, best integrated I have heard, hands down.  Now the Coda, that was a close second but didn’t quite have that last bit of magic, but that is subjective.  Luxman, Acuphase, Pass would be great choices as well.  If you like a warmer presentation from your amps, less solid state out of your solid state but also like some of the benefits of tubes, you likely won’t find a better match than the Krell XD gear.

If you are aren’t dialed in specifically to the Class A’s sound signature, Hegel and Michi are outstanding SS pres’s.  Mac’s should also make the list, some of their integrated will drive just about any separates.  

I would ughly, highly recommend Coda as well and if you give them a call, they might Bias an integrated to pump out more Class A if you wanted.  Their CSiB integrated is available with 3 different amplification options, higher class A but less overall top end or lower class A with higher overall output in class A/B.  Coda might be the best engineered and quality parts brand that slides under the radar.  Their equipment will stand against stuff costing many multiples, it isn’t cheap but the value is off the charts. 

Happy Hunting!  

You have gotten some great advise on the integrated amps.  Krell, Coda and Boulder are the three I would focus on.  I bought a Boulder 866 and it's listed as a AB class but I know it's lower wattage is class A.  Very neutral but very musical.  It is above your budget new but there are always used on the market. 

If youcan spend $6k minus discounts the Hegel H390 

is a excellent choice for its not only very good sounding witha nice natural warm 

but the best control  of your drivers especially Bass witha class leading 4000

damping factor none of the competition are even close 

plus it has a very respectable dac , and even has a very good Roon  ready streamer built in and many software upgrades coming . My brother has one and Perrotta consulting gave him a very good deal and free shipping at almost 50 pounds  shipping is very expensive ,Highly recommended and many excellent reviews.

Well, I asked very specific questions before about what sound characteristics you’re looking for but you didn’t answer and just seem stuck on amplifier topology, so I’m out.  I don’t think PBN has ever designed a full Class A amp although I reviewed one of Peter’s Liberty amps that had low- and high-bias settings and I much preferred it in high bias mode.  My guess is his higher-level PBN amps are Class A/B but skewed toward a higher bias that achieves some of the qualities of a pure Class A amp and maybe that’s what you liked, but that’s just a guess.  


I am in university park, i have 2 class a monos a class a accuphase and a sanders Magtech. The magtech is for sale, it’s not class a but it’s amazing and has basically unlimited power, it has also been upgraded with 6 synergistic fuses, i am selling because im upgrading to a t+a a3000hv. If you want to come listen and compare shoot me a message: I used to be an audio concept’s customer as well

You need to determine how much power you need, ie speaker efficiency etc before you can even consider a Class A amp IMO.  There are not many Pure Class A amp above 50wpc. Most newer ones are 20-30wpc anything above that is switching into Class A/B. yes there are a couple exceptions. 

Thanks for all the advice and suggestions.  I realize now that I'm not tied down to class a.   My tubed power amp puts out 40wpc with the EL34 tubes in.  I can get more with the kt88's but I don't seem to need the extra power.

It seems the Krell K-300i puts out supposedly 90 watts class a power so it appears that is pretty much my only option if I want class a power to spare.

After reading some good folks posts, I'm more open to the idea of a smooth sounding class ab integrated that won't sound puny in comparison to a low watt class a amp.

+1 for the Coda CSiB. I have the v1 which is 150 watts per channel into 8 ohms with the first 18 watts in class A. I use it to drive a pair of difficult to drive Thiel CS 2.4 speakers, and it handles the task with ease.  Most highly recommended.

It's a matter of execution.  I've a Sugden Class A 33 wpc, Luxman A/B 120 wpc. They sound different, but both drive well the ATC 20s, sealed cabinet.  Both exhibit lots of control and drive.

I would suppose the right difficult load could present problems for the Sugden, but I've yet to find that and it's driven lots of different speakers.  The bass from the Sugden is not booming, but it is lightning fast and clean.

Most claimed Class A amps drift into Class A/B after the first few watts anyway.  So then what do we really have?  Just listen with your ears.


Class A amplifiers have no crossover distortion at the 0 point because they use a “single” device to handle a complete waveform. This structure is incredibly power consuming, heat creating, and low on efficiency (usually around 25%) and power (25-30W is an average ouput).

Class B amplifiers use two, or more, devices in a complementary pairing with the “top” one handling the positive half of the waveform and the “bottom” one handling the negative half. The two outputs are then summed to give you the complete waveform with the point that the waveform goes from positive to negative (and back) being called the crossover point. Because of the lack of perfect linearity between devices there will always be some distortion at the point of crossover. Class B amplifiers are usually used for high power work.

A class A/B amplifier uses a class A stage for low power work and then “switches” to the class B stage for higher power work.  

See https://en.wikipedia.org/wiki/Power_amplifier_classes for help, too.

Are you looking for just a Stereo integrated amp? Do you need HDMI inputs? If you are just looking for Stereo and no HDMI, I can recommend Outlaw Audio, I have there RR2160MKll and it is awesome and M8 Subwoofer. It can handle speakers down to 2 ohms has Analog Bass Management has a fantastic phono pre amp. But also has a digital side with internet radio and a nice app for streaming (ethernet port and wifi). Plenty of analog RCA inputs but a couple of toslink digital inputs and a good DAC. They only sell manufacturer direct so it is priced good. It’s a beast!! There headquarters is just a few towns over from me in Easton Ma. https://outlawaudio.com/shop/

Steve Guttenberg does a good review on it here




How do you think any of your post, some of which is wrong, refute or illustrate my post?

The idea that Class A is always lower distortion than Class A/B is simply not correct. It is only correct about one particular type of distortion. Pass for instance is famously and proudly high distortion even in Class A operation.


Hegle is an excellent brand and now is a great time to be looking at the brand. They just replaced the H590 with the H600 and they are selling their remaining H590’s at about half price! The rumor is that the H390, ( which is what I have) is going to be replaced soon with the H400 and I believe they are on sale for $4000 instead of $6000.Both are class A/B and seen to be built like tanks. If I can convince the wife, I’m hoping to get the H590 soon.

All the best.


I could be wrong but I think the Krell K300i is made in the US.  Their lowest model is made in China I believe.