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

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

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.

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.

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

@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..

“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.

@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?

@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. 

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.

@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.....

@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.

"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!

@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?;)

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 "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.

@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.

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!

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?