Originally Posted by Pappas3278
I would have to vehemently disagree with the A2 and "high noise floor" in Low Gain mode with low impedance phones.
I use Grado RS1's and the A2 is absolutely dead quite. My source player is rated at -115dB signal-to-noise and my preamp that is chained to the A2 is rated at -97dB (not excellent). I have an A2 with the transformer hum and it is still...you guessed it -- dead quite.
My A2 also has the mechanical transformer hum issue, but the headphone output in low gain mode is very quiet. No appreciable noise to be heard with my SR60i or HD598.
High gain mode, on the other hand, is a different story. With either of the aforementioned headphones, there's a pretty good amount of background noise. I can still hear a little bit of background noise on my K702 65th Anniversary. With my 600-ohm DT880, I don't hear any noise.
Ultimately, this works just fine for me. The A2 is able to swing plenty of power in the low gain mode to drive my SR60i, HD598, and K702.65. I only ever flip it up to the high gain mode with my DT880/600. No noise floor to be heard with any of those setups.
A couple interesting things to note from Schiit's website:
- SNR: More than 102db, unweighted, referenced to 1V RMS, in low gain mode
- Topology: Fully discrete, single-ended Class A with single voltage gain stage, no overall feedback in high gain mode, 12dB feedback in low gain mode
The SNR figure is given for the low gain mode, indicating that this is presumably the better of the two modes in that regard. I could be wrong, but I suspect the better SNR figure is achieved due to the 12dB of feedback they used in the low gain mode.