tmsrdg - yes sir!
sdl4 - remember, I’m an electronics layman
1. Yes, an AHB-2 should drive your 2.2s. Medium-size and real-world are vague and subjective terms, but here’s why I say yes. The (clipping) protection circuitry is so fast and sophisticated that I can see the lights flickering without hearing any dropouts. That takes 100dB in my functionally rather large room. In case you don’t know, my room was weird. I built a resistive-wall (leaky) 4000 cubic foot room within an 11,500 cubic foot floor of a 38,500 building with various openings between the floors. Virtually no modal interactions, but hard to characterize its "size" since the direct space was moderately sized and the larger spaces were acoustically secondary. All that said, my preference and regular use mode was each speaker driven by a bridged AHB-2. But, a single stereo amp was adequate for moderate (85dB peaks) listening.
2. The AHB distortion profile is extremely clean, but I lack technical fluency regarding your specific question. I point you to the Stereophile and AudioScience reviews, among others, to see their qualitatively (stunningly) low distortion. It took me some time to realize that the bass balance was not thin or dry. Other amps (of my experience) add harmonics, especially noticeable in the bass. On a related note, the Benchmark DAC3 and Preamps-4 take additional measures to reduce second and third harmonic distortion. John Sieu’s essays on Benchmark’s site are quite informative.
I don’t know the Atma-Sphere amps, but I do know that the Benchmark class H topology acts differently than do ’normal’ amps, even full class A. JS sent me some distortion graphs illustrating that the 1 ohm profile is virtually identical to the 8 ohm profile. No, that’s not normal, and no, I can’t lay my hands on those graphs or explain the technicalities. But, yes, the amps do sound that way. With JS’s coaching, I rigged an experiment to account for my initial perception of ’better’ sound in stereo than bridged. The output impedance drops to half, lowering the damping factor. I shortened the speaker cables from 12’ (stereo) to 6’ (bridged) and the SQ difference seemed to vanish. This THX amp topology is amazing as tmsrdg said - all that weirdness goes away leaving only the music. Sorry to gush, it’s just hard for me to believe.
BM has a generous return policy in case their power doesn’t meet your needs. Or, if your budget can be stretched, two of them make for serious audio nirvana.
