Pass....Accuphase....or......

I´m reading a lot about the Coda S5.5... Could it be as good as the A-48?

Have someone tested it at home? With what kind of speakers? How hot does it get?

You have gotten some great advice.  I don't think you would be disappointed with either Pass or Accuphase.  Ralph has also made a great suggestion with class D amps.  I might also suggest the Boulder 866 for your speakers .

The 866 is built like a tank and Boulders are extremely reliable.  200 watts @ 8 ohms and doubles @ 4 ohms.  Also a great company to deal with.

Good luck on your search!

@southofdallas Here’s a little tip if you want the best sound for your investment $$$$.

The amp really should be loafing while doing its work. If your speaker is hard to drive the amp will make more distortion making it go. The result is the amp will sound less relaxed and less detailed because of the distortion increase which will be mostly higher ordered harmonics, to which the ear is keenly sensitive since it uses them to sense sound pressure.

On a speaker like yours if you push our amp too hard it will likely distort. The trick with any amplifier is simply make sure you have enough power so the amp is never working all that hard. Simply speaking you'd have to try it.

The problem is the more power you need for that, the harder it becomes to fine an amp that sounds like music rather than electronics.

@atmasphere "Our amps have an over-current protection circuit that shuts the amp down if too much current shows up."

The speakers I had before (Elipsa SE) went down to around 2 ohms at 100 Hz. It is a big difference then between shutting down and doubling the delivered power to 1 ohm or less. Of course, we are talking about twice the price maybe....and maybe class d is aimed at high efficiency speakers....but still. I can understand why some audiophiles are still buying heavy amps.

if load is lower than nominal, one of devices indeed goes into cutoff!

@westcoastaudiophile That's true of a single-ended class A amp too.

@southofdallas Our amps have an over-current protection circuit that shuts the amp down if too much current shows up. Its got no problem driving 2 Ohms other than that. For example if there is a dip in impedance to 2 Ohms, if the speaker is an ESL that drops to 2 Ohms in the highs its no worries.

@atmasphere "There are class D amps now that easily challenge any class A amp ever made."

Sorry but I just have to ask.... Why do we rarely or never see the power specs of Class D amps below 4 Ohms? Atma Sphere class D is 100 watts per channel into 8 Ω and 200 watts per channel into 4 Ω.... and then? Many 4 Ohm speakers drop way under that. Do they clip? Crash or explode?;)

"Class A means the output device or devices never go into cutoff.” - definition is correct!

push-pull A class amps have bias to cover max current for loads, supported by class a! if load is lower than nominal, one of devices indeed goes into cutoff!

@southofdallas Class A means the output device or devices never go into cutoff.

There are class A push-pull amps and class A single-ended amps, which might be tube or solid state.

Class A is used to get more linearity out of the output section of the amp. If the amp is zero feedback this is pretty important. But depending on how much feedback is used it might be a lot less important, especially in modern designs where more feedback is possible.

Topping makes a line of class B amplifiers now that have exceedingly low distortion. From a designer's point of view, you use class A to reduce distortion, so in a way we can now see that the class of operation is far less important than it used to be. There are class D amps now that easily challenge any class A amp ever made.

If the amp is to be musical, IOW easy to listen to while being neutral, what is far more important is if the amp brings home the bacon in that regard rather than its class of operation! IOW there is far too much emphasis on the class of operation; probably that was important 30-40 years ago but no longer.

@atmasphere then all "Class A" are  AB? Push pull Class A? Pass? What's the point with push pull Class A then? Is the ONLY real Class A a single ended amp? Why throw away the money with high bias AB? Is the heat good only for heating up the room? So many class A amps for no reason.....

A48 is designed as class A amp for loads = or > than 8 Ohms. for loads < 8 Ohms it is a high-bias AB class amp. 

To be clear, 'high bias' class AB amp isn't a thing. Its either class A or its class AB. In this case, class AB. Any properly designed class AB amp will not have an audible 'transition' from A to the B region.

@southofdallas correct! A48 will be more stable at lower load impedance than P4600, which has higher supply voltage.

@lalitk "While the A48s is designed as a Class A amplifier under an 8-ohm resistive load” probably typo, A48 is designed as class A amp for loads = or > than 8 Ohms. for loads < 8 Ohms it is a high-bias AB class amp. 

@westcoastaudiophile @lalitk If I look at the specs it seems to me that the A-48 is the more stable of the two. Doubling the output power down to 1 ohm.  On paper, it does not have a problem with low impedance. Right?

“How much class-A power does the A-48 deliver before drifting into AB”
@southofdallas 
This is why it is crucial to properly match an amp to your speakers and vice-versa. If your speakers dip well below 8 ohms in certain frequency ranges, the P-4600 might be a better choice since it’s designed to handle lower impedances more efficiently while still maintaining excellent sonic 

While the A48s is designed as a Class A amplifier under an 8-ohm resistive load, real-world speakers present a much more complex and dynamic impedance profile. As the impedance dips below 8 ohms, especially with reactive loads from crossovers, voice coils, and cabinet resonances. the amplifier is forced to supply significantly more current.

@southofdallas "How much class-A power does the A-48 deliver before drifting into AB?"

Theoretically A48s always will be in class A mode for full power range, using resistive 8 Ohms load.. BUT, :-), speakers are not resistors, loading applied to the amp is complex / resonating load, at some frequencies much lower effective impedance than rated! For sure A48s becomes high-bias AB class amp with 4 / 2 Ohm rated speakers..

@miguelderivero Thanks! The A-48 in on top of the list....

Has someone compared the A-48 and the P-4600? A and AB? Sound? Heat?

-Hi, Yes I did. But I compared the P-4600 and A-80, not the A-48. My speakers are Sonus Faber Il Cremonese Ex3me and also compare the with McIntosh MC611 and McIntosh 1502. Of all those amplifiers, the winner for me is the A-80. Excellent and clean bass, Mids are just so beautiful with lots of detail and body and the highs are very clean, airy and I can hear detail on the music that I was not aware of with the 611 and the 1502. The P-4600 is a very good amplifier that I will probably said that is more similar with the 611, with nice Mids and a little more extension on the high frequencies but not to the point to be bright. Bass is excellent as well but with the A-80 my speakers reach the bottom of the frequency with more authority and you can not only hear the Mids but fill it as well. My recommendation, A-48. Same character of sound as the A-80. Slightly less power but this Accuphase class A seems like they have much more power than their claimed watts. Good luck on your selection.

FirstWatt is a Nelson Pass "subsidiary." The F8 is class A 25 watts at 8 ohms. Drives my fairly large Revival Audio Atalante 3's, suggested 30 watts, just fine.

https://m.youtube.com/watch?v=q3LK1Mt3CZA

If I were to make a wild guess, I think he just might live 'South of Dallas Texas".

@southofdallas Where do you live? Our class D isn't the only you might consider, FWIW.

@atmasphere It's impossible to find an Atmasphere Class-D amp to test where I live.... sorry. I really would like to test them at home with my speakers.

If I understand it correctly: the Accuphase class-A is a push-pull amp, the same as PASS LABS. Do they leave class-A at some level? How much class-A power does the A-48 deliver before drifting into AB?

@southofdallas This isn't a concern. If a class AB amp had an audible aspect where you could tell it was going into B mode, it literally would not be on your list.

If the amp is competent, the class of operation isn't important. The competence of the amp is! That is why there are class D amps that would do well on your list as well.

Than you @westcoastaudiophile! I listen most to jazz and classical music, I think the new A48S 2x50W is at the top of the list.....unless I win the lottery, then it's the A80.

If I understand it correctly: the Accuphase class-A is a push-pull amp, the same as PASS LABS. Do they leave class-A at some level? How much class-A power does the A-48 deliver before drifting into AB?

@southofdallas I have A48 and P4500.. A48 is better for mid <50W peak power, very smooth/warm, P4500 is excellent for higher volume sounds <150W, rock etc.. P4500 is basically not different from A48 below 5W power.

...and the nominees are:

Accuphase A-48 (upper limit $$)

Luxman MQ-88uC (not enough power…maybe)

Pass Labs XA-25 (Trying to find one to audition or used)

Audio Research Reference 75 SE (...or newer)

Coda (not easily found where I live)

You could consider Coda, cheaper that Pass and Accuphase, but in same class sound vise.

Has someone compared the A-48 and the P-4600? A and AB? Sound? Heat?

+++++ Accuphase A48 great if not greatest <50W/ch SS A class amp! advantage: no maintenance needed for few decades! 

+++++ Luxman MQ-88uC lil less peak power headroom than A48, amazing dynamic range, very low noise floor for tubes, very gentle tubes use conditions to ensure long ride without replacing tubes etc.! 

I have a room your size, with Vandersteen 2CEs and Pass X150s. I would at least consider the 150 series, new or used. Capacity to drive with most of your listening in Class A. I heard a Cornwall IVs with low-watt tubes and I preferred my setup. 

@blue-magoo Man!....those Luxman MQ-88uC look good. And they seem to have a direct input that removes the level control from the circuit. Nice! What kind of speakers do you use with them?

I have the Luxman MQ-88uC power amp. I got it used for about $3000, I changed to nos tubes. If you like a LUSH accurate amp try get one form Mucic Direct and try it out. It's 25 WPC and will easily drive 89 sensitivity . I have used it with Monitor audio, Triangle and KEF speakers. No issues,

I owned Pass, Accuphase, and Audio Research amplifiers and finally settled for the  Ypsilon Phaethon.

These are stellar sounding (harmonious, well defined and capable) amplifiers and their after sales device is incredibly good.

The amp has a discrete volume control with (I believe) 1bB steps.  I am perfectly happy with that, but this is a point of consideration. I own the “normal” version of the Phaethon whith a new price of around €. 18.000,-. 
 

I am confident the you will not regret trying one of these beauties before you make a final decision.

@southofdallas   They are ~98-db efficient at 16-ohms.  

@liquidsound Looks like very high sensitive speakers....100dB?

I have owned two examples of the XA25 and tried them with 5 different speakers. In a medium/large room, I concluded the Pass really need be paired with speakers of a true 90dB sensitivity at minimum. The XA25 is one of those amps that sounds great at most listening levels but for those times you want to push it, there isn’t much headroom. The compression kicks in quite suddenly.

An amp I recently acquired that sounds very similar but with much better headroom is the Ayre V-5XE. You might come across reports that this amp is “light in the bass,” but that hasn’t been my experience. I suspect those anecdotes might have arose from a speaker being wired out of phase, which is an easy mistake to make with the mirrored configuration of their binding posts. It is not a bass monster like some Parasound amps, but it’s certainly no lighter in the bass than the XA25.

All that said, I disagree that the Pass sound is so “unique” that it must be auditioned first, especially with the XA25. If operated well within its limits, with efficient speakers, the XA25 produces end-game sound quality and engagement. 

The Parasound JC5 amp is quite neutral and has far more power than you'll ever need. Great sound, and it can absolutely drive your speakers. It's said that it would cost twice it's price had they built them in the US.

@southofdallas  I have Charney Audio MaestroX speakers with AER-BD3B single drivers.  The drivers are very revealing and the Accuphase gets everything right.  

@liquidsound Thanks. There's an A48S now....2x50W..... What speakers do you have?

I have not heard either the Accuphase or the XA-25, but I have a Pass 250.8 in my system and I think that it is a great and powerful amp that drives my Wilson Sabrina X's perfectly.  Paired with a good tube pre (I have an ARC REF 6), its a great combo.

+++++ for Accuphase  I have an A48 and its power and finesse is terrific !  Well built, wonderful sonics, superb reliability and LOVE those VU meters !  

@atmasphere Thanks! "Ambient signature" sounds very good to me. I´ll remember that expression.

@southofdallas I've recorded stuff in the same halls I've played in. You get a sense of the hall and I wanted that in the recording. Each hall has a different sound to it so I describe that as the ambient signature. So yes, the ability to express that seems to fit with those terms (space, scale, spaciousness).

@atmasphere What do you call that in Hi-End audio language then ....if I may ask? Space? Spaciousness? Scale? .....

@southofdallas  Thanks!

I don't know that hall but I've played in a number of them here in Minnesota (bass in several orchestras so O'Shaughnessy, Orchestra Hall and the Ordway). I know what you're talking about but I'd never have thought to call that 'air'.

@atmasphere "I always associated 'air' with ease and space in the highs. I've not heard of it used in the context that you do; probably a topic for another thread. "

Pretend yo are in the Berliner Philharmonic concert hall....you listen to a big orchestra playing very powerful music, the volume is high but never compressed, it is just floating around (not only the highs). No speakers in this world can do that but our ears together with our brain can let us imagine that we are there when we listen at home. Nice.... 

Well, I do like the sound of my 89dB speakers so they stay for now.

@southofdallas This is exactly why its a good idea to use speakers that are easy to drive. You don't have to sacrifice any resolution to have easy to drive speakers. Lower efficiency speakers tend to have something called 'thermal compression' which is caused by heating of the voice coils. The higher the efficiency of the speaker the less compression you get.

When a slightly lower power amp is driving higher efficiency/easy to drive speakers you find you can get the same effortless quality.

I always associated 'air' with ease and space in the highs. I've not heard of it used in the context that you do; probably a topic for another thread. 

@atmasphere Relaxed, yes (laid back, no) effortless presentation is probably what I call "air" in the music, as in a big concert hall. "even at higher volume levels"...then you need dynamics, otherwise it becomes a  flat/compressed presentation. I don't now about the tricks with distortion, you have to talk to Nelson about that ;). The best amps I ever heard were BIG Audio Research monoblocks and BIG pass Labs, talk about effortless! But I can´t afford such a system....That's why I listen to live music whenever I can.....after all: it's the real thing!

I drove mine with a few different amps, the Luxman M800 was probably the most solid with them. That was 60/120. The 590 was okay the 550AXII for low levels. You need to hear a few amps and align with your preferences and circumstances. I’ve had a few Ayre amps, dealer friend demos but liked the Luxman better.

One great sounding combination I heard them with was the Audio Research Ref 110 with Ref 3 preamp.

As for lighter load, I would guess that the impedance curve on these isn’t horrible, but agree with Ozzy you wouldn’t call them high efficiency. I owned the Otello’s, much easier to drive with 93db eff I think. I’d say they Otello's are on the lower side of higher efficiency at best. Drove those great with 30 wpc tubes.

If @grislybutter is right, the OP should be checking out some good SET amps. Why mess around with these Class A SS amps, go straight to a good 2A3.