I have an old review of the O2/ODAC when it was new. I bought it specifically for the HE-400s. I need to edit the review a tad (in it I talk about hiss, which I now know was totally the laptop as source, not the amp).
The change was, Laptop -> O2 ->O2 + ODAC
In short, they make a fine combination. Definitely superior sonic quality compared to the laptop - black background, nice punchy dynamic sound and so on. But I would caution that the audio quality wasn't NIGHT and DAY better, just a clear step up in some ways. The most important aspect was gaining additional power so I could reach the SPL I wanted with the HE-400 under different listening conditions. The ODAC is great, but gave me more buyers remorse as I realized the DAC in my computer sounded more or less the same. But the totally black background of the combo is pretty awesome once you get used to it!
Thanks for the heads up!! May end up getting the Schiit combo..
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