Some thoughts:
Most people will probably use TAK in combination with foobar2000 or Winamp, and therefore the only logo they will see is the logo of the playing program.
For example, I associate lame/MP3 with the red foobar2000 logo and not at all
with the official logo.
We already got a
blue-ish foobar2000 icon. I don't know how winamp does it's icon management though...
If you need a logo I'd go with the blue one from Insulent.

It's got that modern "web 2.0 look", is easy to the eye, it is blue like the foobar2000 logo, and you could easily wrap a good looking website around it.
I think a text-based logo is really the only good way here, as finding an appropiate icon to "TAK" might be very difficult.
Please don't do a wave, speaker cone or VU meter logo, because we already got enough of them (Musepack, FLAC...)! This is the most obvious way of doing a logo, but also the most blatant and unoriginal one. A good example for an icon-based logo is the Vorbis/Xiph fish, as it is very distinctive and recognisable.
QUOTE
Well, there have been more great and very interesting logos, but some seemed to be not suitable for different resolutions (especially icons).
I guess you don't need to worry about that. The files itself will probably have the foobar2000/winamp logo. And for your GUI you could use just the 't' from Insulent's logo.