My work computer’s on-board audio wasn’t all that great, being an mITX motherboard. It had all sorts of very audible interference. To get around this I bought a cheap USB audio device from eBay. Unfortunately when it arrived I found its output to be very tinny and lackluster.
Opening the device I found two very inadequate 10µF surface mount capacitors. These might be suitable for Skype headsets but not for headphones. Following a friend’s advice, headphone drivers should have 470µF output caps. I used four 1mF polarized capacitors back-to-back as two 500µF (close enough to 470µF) bipolar capacitors.
The result sounds fantastic; lots of bass. :3