Have tried the Pass Aleph series on Martin Logan's and they were exceptional.
The one's I've heard are the Aleph 0 (stereo version, not the 0 mono's), Aleph 3, Aleph 5 and Aleph 2 mono's ...on Aerius i's and SL3's.
The Aleph 3 drives the speakers, sound quality is great, but I did want a little more power. Aleph 5 or Aleph 0 would be plenty for me to live with, and Aleph 2's would be a wonderful extravagance.
Heat and power usage are issues, the amps run full power, all the time (pure Class A) ...so they are little heaters and burn more electricity than A/B amps.
They sound best left on, so its annoying to shut them off to save buring the watts. For heat, one amp should be fine, stereo mono's in a smaller room, left on all the time, could be a little hot, especially in summer. I'm thinking of this because you'd mentioned a home-theatre and possibly mono's, ...so 5 or 7 amps running full Class A, ...would sound great, would be hot too (?).
They suit Martin Logan's because they can handle the deep current and they are masters of the whisper light details - as delicate and nuanced a touch as you'll get. On the power, note that the Aleph series don't put out any more power below 4 ohms, because they have just the two gain stages (one of the reasons they sound so good is the simple *pure* design) ..., they are completely stable well below 4 ohms, below 1 ohm likely, its just that they don't put out more watts at the lower ohm levels.
A good preamp is required to get what these amps are able to give,...otherwise the strengths will be wasted and you'll be better off with less costly amps. For example, the whisper light details and nuanced touch I talked about won't mean much if the pre is too clumsy to let them get through. The Aleph P preamp is an excellent match,....the Adcom GFP-750 is a very good budget alternative (designed by Nelson Pass,...also has theatre throughput).
At one time I was running a Sony XA7ES/Wadia 301 --> Aleph P ---> Aleph 5---> Aerius i/SL3 ,...and the sound was extremely good, ditto for the Aleph 0,...Aleph 3 had not quite enough volume.
Customer service from Pass Labs was outstanding in my experience. A friend borrowed my brand new Aleph 3 and broke the binding post by taking a socket wrench to the binding posts and doing the cave man. I told Pass that the post was broken by user abuse, idiotic over-cranking with a long handled socket wrench - Pass took them amp and put a new binding post on and shipped it back free of charge. It turns out that I was the original owner, from a proper dealer and the amp was just new etc.,...But Pass Labs didn't even ask - they just fixed the amp and had it back to me in a hurry. I was thoroughly impressed. And I've heard nothing but good experiences from others about Pass Labs service and Nelson Pass (the service people said its rare they get something to do, so were happy to jump on the case
The X series and anything newer, I haven't heard - though they're probably great too.
The comprimises are cost, heat ,just moderate watts, need of quality preamp,...the benifit is exceptional sound quality.
Martin
