Pros: Class A Sound
Cons: More of a headstage, cosmetically the LED does not match the Bifrost
Mike and Jason have now successfully parted me with a tidy sum, but when I listen to their gear I smile. I have an old pair of Grado SR-225's that I now realize I have never really heard. I had already owned the Bifrost for my stereo but I had been driving the Grados with what was to me a nice sounding chip amp but I got tired of feeding the hungry little monster pairs of 9v batteries.
I could wax prophetic for a few paragraphs but I will spare you the agony. The sound can be summed up as that sweet even order harmonic clarity characteristic of single-ended circuit designs. For me there is nothing that comes close to the purity and musicality of a single-ended class A amp.
The first couple times I put the phones on I had that sort of initial adjustment that I sometimtes get listening to my SET amp; it's sort of a feeling of being mentally jarred by the clarity of the music. The sound is neutral and well balanced, has the ability to handle big dynamic swings and the separation of instrumentation is excellent. It produces more of a head-stage than a sound-stage but maybe that is the Grados. Noise floor is non-existent, even on the sensitive SR225's. Oh and yeah...for the record, no need for A/B listening; the Asgard totally smokes the chip amp. I was expecting subtle improvement but the two are in totally different orbits.
In sum if you are ready to step into the world of dedicated headphone amps, I find it hard to believe anybody with a decent set of cans would be disappointed with Asgard. Given the reasonable price it can't be ignored. Oh, just in case it hasn't been mentioned in any of the 1,600 posts in the appreciation thread it runs hot - really really hot (and stinks a bit when new) but hot-running amps usually sound good. I do beg to differ with the instruction manual, it is an excellent coffee warmer...warranty be damned.
Here is how I listen:
#! Linux running MPD > USB > Bifrost > Asgard > SR225