40+ watts SET, cost is not a problem

+1 @dogearedaudio - Berning 211 / 845 Monoblock Amplifiers

I've heard, and generally liked the Berning amps I've heard.  I don't care if they are, or are not, true output transformerless amps  (OTL).  To me, they have that immediate, exciting and vivid sound of OTL amps.  But, like ANY amp choice, it does come down to personal preferences.  For my taste, Bernings are on the slightly too lean sounding side.  But, I suspect that the OP IS looking a bit in that direction so they are certainly good candidates.  

I know the OP is looking for some fairly high end amplifier/linestage combinations.  Still, I think there are some shockingly good value amps that should at least be auditioned.  Again, Synthesis Audio makes super bargain amps that I would be perfectly happy to use in my system.  They do make some fairly pricey high-powered amps, but my personal preference is for the amps that run the KT-66 tube and the best from them is a pair of monobloc amps that cost "only" $20k or so.  

Having heard multiple Berning amps, they ultimately sound a bit sterile to me because of the switch mode power supply. If an audio designer can't even hear the basics of music and figure out what is lost with a switching PSU and just uses it for specs, I have no respect for such designers. And the industry is full of such people. Thats why high end audio is so difficult to get right, musically :-(

Reach out to Aric at Aric Audio for his take. Perhaps something bespoke is what you seek and what he can likely deliver.

the listening distance is indeed near field (6-7 feet from the plane of the speakers). However, I do understand your point of these speakers needing a lot of power. Why do you suggest Class D and not A, AB ?

@pani Most solid state amps lack the Gain Bandwidth Product to support the feedback they have. As a result, at some point in the audio band (often, only 1KHz), the feedback begins to decrease on a 6dB/octave slope, often faster as frequency increases. Distortion thus rises on a complementary curve.

This sort of thing is audible, usually as harshness (since higher ordered harmonics are unmasked in this manner) and brightness (for the same reason).

OTOH its very easy to generate enormous Gain Bandwidth Product with a class D design. That makes it possible to have feedback with no rise in distortion anywhere in the audio band, much like a zero feedback amp but with lower distortion, which results in a more musical presentation with greater detail. Some class D amps, as a result, can sound every bit as musical and involving as the best SETs, with greater transparency.

’Nearfield’ is usually about 3-4 feet FWIW. If you really are limited to that distance you might find a tube amp that can do the job. The reason the Sensitivity spec (2.83 Volts/1 meter) is used is because solid state amps can double power as impedance is halved. Being able to do that defines the amp as a Voltage source and that is what the speaker is designed for. Tube amps can behave as a Voltage source too, but do it by cutting power in half as impedance is doubled. So tubes tend to be a lot more expensive on that account. Since tubes don’t double power as impedance is halved, the Efficiency spec (1 Watt/1 meter) is more useful with tubes because it tells you at a glance if you have enough power. 83dB in my room would require 800 Watts(!) and I really don’t know of anyone making an amp that is that powerful and also sounds like real music.

Consider that if you had a speaker of 93dB you would not need to take a hit on resolution or bandwidth, but the amp needed would be a 10th of the power. So you could do the same sound pressure with 80 Watts instead of 800 in my example just above. Now its easy. If nearfield you really could use an SET (although not to its best advantage).

Right now its simply out of the question. If you want to do your friend right, really think about a different speaker.

Having heard multiple Berning amps, they ultimately sound a bit sterile to me because of the switch mode power supply.

Its highly unlikely the switch mode supply has anything to do with what you heard! When you hear differences in amplifiers, again its the distortion of that amp that is its sonic signature. The SMPS is operating at 250KHz in that design; you’re not going to hear it. IOW I get that you might not like the sound of the amp but the SMPS isn’t why it sounds that way.