Doesn't the Karma use the same Wolfson WM8731 headphone/DAC (CODEC) combo IC that most of the recent iPods had been using? I believe these provided 50mw at 16 ohms impedance which works great for Grados but not so well for 300 ohm Sennheisers like my HD-600. If mated to my iPod, I get fair volume and bass, but nothing spectacular.

Stu