This isn't scientific in any way, but I wanted to get down some of my impressions of my new Schiit Magni after a day of listening. Most of what I'll be talking about is how the Magni works with my MSii+ and HE-500. My other gear consists of an HD650, the FiiO E9, and the JDS O2. I've been listening to Spotify high quality, 320 mbps mp3, and certain albums ripped into ALAC on iTunes.
First off, I think I've finally found an amp that does my HE-500 justice. When I first got the HE-500 and jumped from the HD650, my impression was that although the HE-500 is much clearer, it collapsed the sound stage in a way that the HD650s (on either the E9 or O2) just didn't. It also took me some time to adjust to the HE-500's lack of mid-bass hump that makes the HD650 such an enjoyable headphone. I couldn't enjoy the O2 at all with the HE-500, as normal gain didn't drive them loud enough and increasing the gain caused them to clip. I've since been told that I can improve the AC power source and that the O2 is a mismatch with my MSii+. If I had it to do over again, I'd never have bought the O2 - I was set on getting a Schiit amplifier before I read about their early problems with blowing headphones before they added relay protections into their amps. A lot of bad things were said about Schiit as a company by the O2 people and I found myself influenced by the 'objectivists' about how an amp should be a transparent 'wire with gain'. I'd hoped that I'd get that with the O2, but the O2 totally failed to power my HE-500 and after a bit of time, my connection at the headphone plug-in degraded to where I had to adjust the cable to get both left and right to play correctly.
Since a common opinion of planar magnetics is that they have a reduced sound stage compared to the best dynamic drivers (HD800), I assumed that my collapsed sound stage was purely due to this tendency of planar magnetic headphones. Another issue I had with the HE-500 is that they seemed to put me at an analytical distance from my music. Where heads would bob and toes would tap on the HD650, no such unbidden movement occurred when listening with my HE-500. Since the O2 was a no-go with the HE-500, I used them primarily with the E9. The E9 did an admirable job driving them to appropriate listening volumes without clipping, the soundstage was still a cluttered mess.
With Schiit releasing the Magni at such a low price-point, I decided I just had to try to find a way to amplify these headphones better. I wasn't sure, but I could sense that I wasn't getting all that I could out of them - and I have to say that after running them with the Magni, that impression was totally correct.
With the Magni, my HE-500 suddenly have a sound stage! The HE-500 are clearer all around and the bass is very controlled. Instruments have more of their own space and upon reflection, the E9 is actually a warm amp in comparison. The Magni also induces a lot more head-bobbing and toe tapping (this is actually a bit of a danger to one's neck with the HE-500, but nonetheless, I can't resist!). One of the best genres improved by the Magni has been, surprisingly, electronic music. When I listen to BT or Infected Mushroom with the Magni, everything is just so crisp and clear that what I'd perceived to be a weakness of the HE-500 - that they resolve so well that they make the repetitive nature of sampled music sound bland compared to 'analog' music - has gone away. Notes and instruments have more subtlety than I'd imagined and the improvement in energy (the toe-tapping effect) and sound-stage with clear instrument separation is allowing me to enjoy electronic music much more than I thought I could.
If there's a negative to the Magni, it's that it brings a bit of etching and transparency to indie music that isn't flattering to the way the albums are often recorded. The warmth of the E9 can actually be a bit of a blessing in that it masks the flaws of the recordings better.
I've briefly sampled the Magni with the HD650 but I'm having difficulty separating the differences in transducers (and getting reacquainted with that mid-bass hump and relatively wallowing bass) enough to tell if the Magni is improving it. A/B testing with the E9 is difficult because it's hard to find corresponding volumes.
I hope to add more later, but for now I just have to say that I'm delighted with this inexpensive amp!