I use UE900 silicone tips. The T-500 tips are nice and comfy, but are more difficult to insert and have to be cleaned/replaced regularly.

There are only three 24 ohm resistors and three 0.1uF capacitors listed on thr BOM.

Also, IC1 on the board is IC2 on the BOM, and vice versa.

Same question with R5?

Quick question: what's C8? I don't see it on the BOM...

Here's a cheap wall wart on Amazon, if anyone's looking!   http://www.amazon.com/AC-AC-ADAPTER-9VOLTS-1000mA-2-1mm/dp/B00ATECBMM/ref=pd_cp_e_0

Sorry, just to clarify, the power can also be 6-9 VDC? Or is it limited to 6-9 VAC?

Personally, I use HDTracks.com and similar sites, since they offer high quality files. Usually, though, I just buy physical CDs and rip them. That lets you rip it into any file type you want, up to a lossless 44.1/16 file, which is better than most download sites! Plus, you get to have a...

I'm definitely interested! I know this is being made in the spirit of the PPA, but has there been any thought on exactly what kind of output power this would have? And (dare I ask) final cost?

Well, my recommendations were based on the assumption that you want something cheap and neutral, and in retrospect, I totally recommended you stuff I've never even listened to before! Just a heads up, so that you don't go buying something on my word alone.   The Schiit Magni is pretty cheap at...

Honestly, I'd be fairly surprised if you can even get a decent volume! I don't know what 990's are like underamped, but generally I believe underamped headphones have a smaller soundstage. If you want portability, an E12 might be the best bet (over 4 times the power at 32 ohms). Other desk...

Your headphones are 250 ohm impedance? Probably won't do you much good... But try them out, and return if you don't like it!

Good! You're gonna like what you hear. I guarantee it.  

Well, best of luck with that! Just be aware that the E11 won't do you much...

If you're not looking for portability, a used Schiit Magni would be good! Personally, I power my Mad Dogs from a Fiio X3, and it's pretty good on high gain. I'll use an amp for more critical listening sessions, though.