Pass x250.8 vs Boulder 850 vs Spectral DMA250

@Zd542 definitively yes. BJTs that George suggest are valid and with no doubt they potentially drive the SF at their best. But the sound pressure I can drive these speakers is for a normal listening room (50sqmt in this case) so the power request can be managed also by Bouldes or Pass.

If you know the SF Elipsa Red or Stradivari sound, they have a wonderful bass but it needs a lot of control.

First I was oriented to pure Class-A amplifiers but when I realized that most of them are monos -and I don't have space for two amps- I was looking elsewhere.
From the George list I guess the only amp I can ask for a test is the Ayre.

Sure I will test all initial three.

My dentist plays with the first generation Amati's. He uses Krell amps of about 7 years old. The sound is stunning. I heard these also with ML. It sounded dead, without emotion. Even depth was of a very low level. Yes SF needs power and speed, because SF does not use units with the best response. You need a lot of power and speed to solve this limitation. But....also you need emotion. It is easy to get a clinical sound out of a SF. I love classical music with SF. I think SF will be my new brand in speakers I will start to sell. I will use SF for it's design and for the options of more expensive speakers.

@Bo1972 It is not a mistery that Franco Serblin (r.i.p.) tested its own products, in the first instance, with Spectral, his personal setup, and (maybe not confirmed) Krell stuff.

In 16 years of time I heard many spectral demos. There was
not even one time that it gave me a smile on my face. What I
said earlier; in a few seconds I can hear to all different
parts which need to be there. There is a lot missing with
Spectral in my personal opinion. In a few demos I really
liked the speed and depth. But.....other things were still
missing. For me this is incomplete. I don't want it. I prefer
and even demand a small and realistic intimate sound. I never
heard any Spectral do this as I want it to be. I hate
classical music played by spectral. It irritated me a few
times. I asked the dealer;do you think a violin sounds like
this? I said: it sound like a clinical violin. That is not
how it sounds in real. This brand I also not even want for
free. Pass labs is superior in emotion compared to Spectral.

"08-19-14: Maz65
@Bo1972 It is not a mistery that Franco Serblin (r.i.p.) tested its own products, in the first instance, with Spectral, his personal setup, and (maybe not confirmed) Krell stuff."

Speaker manufacturers test their speakers with a lot of different amps. They have to make sure the speakers work with a large variety of products. Aside from Krell and Spectral, your speakers were probably tested with another 10-15 amps. At least.

Bo's right about the Spectral amps. They do have a unique sound. You may like it, but there's no way I would buy them without listening to them first. Also, with the Pass amp, you can't put it into the same class as other mosfet amps. Pass is the best guy there is with mosfets. He gets them sounding just as clean as most bipolars. Another amp you may want to look at is Ayre. They do use bipolars, but they don't sound like anything else. For solid state, Ayre is my favorite. But whatever you decide to do, you need to listen for yourself. Going by reviews and opinions is very risky.