"That's where I discovered that my new hero amp wasn't quite perfect. Oh, its power and resolution were still not to be faulted, but through a pair of Monitor Audio Silver 8 speakers, the sound was somewhat hard and thin. Could it have had something to do with the Silver 8s themselves? While that speaker's minimum impedance is 3.5 ohms at 165Hz, but with a benign phase angle,
JA points out that "there is a combination of –34° and 4.5 ohms at 100Hz, a frequency where music can have high energy." Still, he says, "A 4 ohm–rated amplifier or receiver will have no problems driving this speaker to high levels." If so, I would expect the Benchmark AHB2 to be more than up to the task.
But here's how it played out. A 16/44.1 PCM file ripped from the above-mentioned Theessink CD seemed robbed of some of its warmth and resonance. Familiar recordings of women's voices, such as Marianne Beate Kielland singing Finzi's "Come Away, Death" (with pianist Sergei Osadchuk; 24-bit/192kHz PCM download from SACD/CD, 2L 2L-064-SACD), and Sara K.'s cover of "Can't Stand the Rain" from her
Hell or High Water (CD, Stockfisch SFR 357.4039.2), sounded strange. Both voices were higher, not in pitch but in tonal range, as if they'd been transformed from mezzo-sopranos (which Kielland is) to sopranos. Again, I would describe it as a loss of warmth and resonance in the fundamentals of their voices. Unfortunately for the AHB2, this loss pervaded the sound of whatever recording I played...
...Back in Manhattan, all seemed better again with the AHB2—except for one troubling event. I've been ripping my CD collection to my 16TB NAS for a couple weeks (already it seems like months), and have become randomly reacquainted with some old favorites—such as the marvelous Emma Kirkby singing Mozart's "Exsultate, Jubilate" (with Christopher Hogwood and the Academy of Ancient Music; CD, L'Oiseau-Lyre 168055), which I hadn't played in ages. Sadly, the divine Dame Emma sounded to have aged badly on this 1984 CD. Akin to what I'd experienced in Connecticut, her voice was robbed of its bell-like richness by the AHB2, only to have it restored when switching to my other amps."
https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-page-2#LMgAqtmbYK72m5zt.99