I've had a new SET-120 for a month now, driving 93db efficient 12ohm Spatial M4Triode Masters. So I wanted to second Frank's comment on power needs.
I'm new to this circle, so a brief introduction. In 1966 I began this hobby with a Dynaco Stereo 70/Pas 3x with AR4x speakers and AR turntable. Since then I've put together many systems, all which I'd categorize as no more than "budget audiophile."
I've used the AVA SET-120 with two preamps.
First, combined with Spatial M4TM speakers and a cheap passive preamp, the SET-120 is capable of thunderous and clear reproduction (at levels 95db+ at 10 feet away) that would soon lead to hearing loss. And at that high sound level, the potentiometer of the pre is at about 12 o'clock.
Second, the Spatial M4TM speakers/ SET-120 combination using my 18-year-old 12sn7 Mapletree preamp with 20db of gain. The sound is balanced across the spectrum, soundstage has good depth and is much wider and higher than the speakers, and on the romantic side of neutral (mostly due to the tube pre, comparing the result to the passive pre that I mentioned above). With the Mapletree preamp I can't get beyond about 10 o'clock on the potentiometer. I suspect, at the levels I normally listen, below 85db, the SET-120 runs exclusively in class A.
BTW, a couple of posters on the Spatial Audio circle had reported very favorably on their results with Spatial M3s and M4s driven by SET-120, which led me to AVA. It was good advice.
Thanks to Frank for a great amp at a bargain price!
Tom Mitchell