As Tom has said, this appears to be normal.  I have some suspicions as to what causes it, but haven't had time to track it down.    It does appear to be related to spikes on the mains power that get fed into the dac (either via to output or the PC side).  Similar kinds of things happen when...

I have a few ideas kicking around, but given that it's just ideas at the moment, there is no comments about anything either way......

I'll admit to not having looked at the circuit in quite a while so it would take me a few moments to figure out the limits with the "default" BOM we spec'ed. That doesn't mean that you can't spec out a different set of parts to meet a specific need. With the proper choices for parts (and...

This was by design to keep the straightest path from the PCM1974 to the outputs. They follow on the same side as they are on the chip. Otherwise I would have had to cross traces on the board, and I didn't want to do that for various reasons. As for the values of the caps, so long as they are...

For our purposes they are exactly the same. The choice of part for the kit is based upon availability. IIRC, the difference is based upon the PCM2706 being programmable by an EEPROM.

The AD797 isn't spec'ed to run at +-2.5V, which is what the output opamp is running at in the pupDAC. With some careful looking at the schematic and board, you may figure out a way to get +-5V, but I'm not going to say anything about how it would actually work.

I agree with your point, but one thing to be aware of is that the negative rail generator can only create 60mA before it limits. So, yes it can drive headphones. But at loud volumes or larger current requirements, the negative rail to the opamp could collapse in all sorts of interesting ways.

My understanding is nothing is "wrong" per se. The issue, again to my understanding, is that some of the part numbers in the kits do not match the part numbers on "the BOM". This will mean that you as builder may need to take a step or two more to ensure that you put the right part in the right...

I'm glad you like it. I would agree that the clean sound of it is something that can take a little while to appreciate. ;)

I almost want to see that happen, just to see it. :D I think you'd want to get Blendtec to see if it will blend first.

The Pimeta V2 has the trickle charger built-in. The Pimeta V1 needed it added on. If you google it, you will find schematics for what you need to build (and maybe even an explanation of how it works).

Making it chargeable without removing is easy. "Trickle Charger Pimeta" are your magic words. I just looked at your source link. You need to read the MintyBoost pages. Many devices need special tweaks to the D+/D- lines to charge properly.

Why not get a MintyBoost? http://adafruit.com/products/14

tomb always seems to put together excellent kits. As for the sound compared to my other designs, neither tomb or I will tend to comment as we have both interest in the design. Hopefully someone else will make comments for you.

The only recommendation that I can suggest is to try and decide what you like.