I am hoping you can shed some light on an acrimonious debate between my friend and me. My friend is a fan of nwavguy, and he insists the 32 ohms output impedance of my Little Dot 1+ is disastrous for my Denon D2000's (which have 25 ohms impedance). Sometimes I suspect the amp is overpowering the cans; rarely can I raise the volume past 9 o'clock. I have seen people recommend a 1:10 ratio of output impedance to load impedance; if that advice is correct, it would seem terrible that the LD actually has a higher Z than the Denons! And yet everyone highly recommends this amp for Grados, Denons, and other low-Z cans, so I am puzzled.
On a semi-related note, my friend and I listen to a lot of acoustic music, especially harpsichord recordings by Gustav Leonhardt, which I think tend to be closely mic'ed. I hear all kinds of background noises on these recordings (performer moving/grunting), and on some I hear continuous, unpleasant low-frequency noise, almost like a dull roar. Sometimes the bass noise comes across as a kind of pressure, more felt than heard - hard to describe; is it an effect of closed cans? I am using Voskhod EF95 tubes, OPA2107, and the HRT Streamer 2 with lossless files as a source. My friend claims he hears none of these problems, or he hears them so little they're not distracting. He is listening to the same CDs, using Grado 325i, Grado RA1 and a portable CD player with line-out. So, the essence of our debate: I believe these particular recordings are awful because I don't hear problems with any other ones, and perhaps his cans or DAC are obscuring details. He claims the recordings sound fantastic to him, and there must be a problem with my setup: perhaps the bassy response curve of the Denons is revealing noises the recording engineers did not intend to be audible; perhaps the impedance mismatch is causing bizarre, unpredictable distortion or imbalanced response at certain frequency ranges, etc. It is worth noting that the Grados and the Denons have opposite response curves in the midrange, so perhaps he simply doesn't have to turn the volume up enough to hear the noises badly.
There are perhaps 2 other things worth noting: (1) the low-frequency noise problems seem to be better with my new Voskhods (previously, I was using WE408a's which came with the amp, and one of them was quite microphonic), and (2) the problems I heard on Leonhardt's CDs were not any better when I tried a JRC cmoy amp, which should have near 0 output impedance.
So, can anyone explain this bizarre disagreement between us? I would be delighted to hear other people's experiences of the LD 1+, the Denons, or especially both together. And if anyone has listened to lots of Gustav Leonhardt and can settle the question of the recording quality, I'd be ecstatic! On almost all my other records, the LD 1+ / Denon combo has sounded fantastic.