Not sure if this belongs in this thread or the general discussion thread, but both threads seem to have the same posters :)
I received my D1 a few days ago. I've been using it for two things so far: as a sound card replacement over USB, and as an amp/volume control device for using headphones with my PS3. For the former, paired with my AKG K-702s, I was pleased. Detail and soundstage were both markedly better than what I had experienced with my Total Bithead (which died due to me being a clutz).
For gaming, I prefer closed headphones. I plugged my PS3 into the RCA analog inputs and hooked up my ATH-A900s. Immediately, I was overwhelmed with hissing, crackling, beeping, and a constant high-pitched whine. Some of this noise is coming from the USB input. Unplugging that removed a bit of the beeping and crackling, but all the interference and/or feedback is present even with nothing hooked up at all. Just having the unit on and the headphones plugged in is tremendously noisy, regardless of the volume setting. I can also hear the high-frequency whine regardless of the input setting. Perhaps it's because the ATH-A900s only have 40 ohms of impedance?
The K-702s, with their 62 ohms of impedance, aren't nearly as noisy. But there still IS noise, especially when the USB input is enabled. For my computer, I have ordered some optical and coaxial cables to try because the USB function is very disappointing. Bypassing it should eliminate some of the issues.
For reference, both the D1 and my computer are hooked up to a high-end UPS with power conditioning. I don't think the issues are due to grounding. I briefly used the tube preamp output with a Y-adapter and some cheapo headphones to see if the noise was present there (I know the preamp output is "hot" so I didn't want to use anything worth more than 50 bucks). I couldn't hear any noise, but this is probably only because the preamp output is so much weaker.
So, is my unit defective, or am I wrong for using this with such low-impedance headphones? I'm not even going to try some of my in-ear monitors. I'd likely go deaf from the noise.
Edited by Blagnoth - 12/18/11 at 11:30am