Most Honda radios now feature USB in with iPod support, and analog in.
Using USB, you get knob-control of :
1) an iPod
or
2) any folder which it can browse on a USB drive or MP3 player
Probably 16 bit only, and probably can only manage 8 or 16 gb of drive, even if on an MP3 player
Analog, it just amplifies whatever comes in and the player does the A/D and file management
I hope that helps, YMMV...