It appears the headphone is driven from the tube only, and not a tap from the speaker outputs.  The power supplies to the preamp and amp are separate, and the device even requires a mini to mini cable to connect to the preamp to the amp (strikes me as a bit silly, but whatever).  The pictures on...

This thread may look absurd on its face - a maxxed WA2 or Zana Deux cost almost an order of magnitude more than the Bottlehead Crack.  However, all of these OTL amplifiers receive rave reviews, especially for my go-to cans (HD 650).  Would anyone who has listened to the Crack (with or without...

Complements on a very thoughtful, detailed review.

Very interesting!  Not sure I am going to run out and do this with my HDP, but appreciate the knowledge :')

Strong - thank you for the tip.

I have a NuForce HDP and I find it to be a great match with the Senn HD650.

Out of curiosity, does an AD USB isolator chip provide galvanic isolation?  Saw this term yesterday on the computer audiophile blog and was not previously aware of this issue.