I'm running mine from a Bifrost Uber, with either a macbook Air via USB or an iPhone 5S via a Pure i-20 with a 30 pin to lightning adapter, coax out and coax into the Bifrost. I have an unnamed for now highish end all in one with a class A amp section and an ESS 9018 dac. The all in one is much more aggressive at showing details, giving it the impression of being much brighter. I find the Asgard 2 / Bifrost to be a bit more relaxed, in a positive way. I ran into this same thing with a Northern Fidelity NF DAC (reviewed by project86 for those interested. Nice dac, not many around) and a Burson Soloist SL. I finally narrowed the differences down to the two dac implementations. My initial thoughts are that the same issue exists with the all in one and the Asgard 2 / Bifrost Uber. My guess is the amp sections are gonna be really close in sound, and the Dacs are gonna be where the difference comes from. Once my RCA "Y" splitters come in, I'll be able to run same dac to both A2 and all in one amp sections and do a bit more comparing.
What's my point? Maybe the brightness is a case of the A2 revealing the source's characteristics?
After a couple hours last night - I am quite impressed. The Asgard 2 is better than I thought. A nice black background and no noticeable noise on high or low gain. OK, shut off the music, and max the volume, and a little hum leaks through. Nothing down in the listening range of the volume pot, and nothing when music plays. The A-2 seems to be a good, clean amp. I like the pairing, and tend to use high gain with the PM-1, though low gain works fine. With my Alpha Dogs, high gain is required. Low gain will drive them, but you can get to full travel on the volume pot without getting to ear bleed levels.
I think the Bifrost Uber has a fair amount to do with my experience with the Asgard 2. The Bifrost Uber is a really nice sounding source. The Asgard 2 seems to get out of the way pretty well. I've read comments that it is not as musical as some amps. I only have the unnamed all in one to compare to, but the all in one is a couple of tiers up in product placement. The Asgard 2 compares very well. I'd like to find a comparison to the Burson Soloist or Soloist SL, as I find the Bursons to be very musical to my ears.
I was all set to get a Lyr, but didn't think it would pair all that well with the PM-1's so I went for the Asgard 2. It is a nice pairing with both the PM-1 and the Alpha Dogs. I really want to do some comparisons to summit-fi gear at the July SF Bay meet, and see whee it really stands. For the price I paid used for the Bifrost uber and the Asgard 2, it seems so far one heck of a value.
Caveat - all impressions after only couple hours, so the new toy / fanboy syndrome hasn't worn off yet. Still, I am pleasantly surprised.