I've observed USB audio seems to fail in El Capitan Developer Preview 1 using a CEntrance HiFi-M8. This device supports a range of 2 channel 24 bit formats (44.1KHz, 48.0KHz, 88.2KHz, 96.0KHz, 176.4KHz, 192.0KHz, etc.). While it worked just great in Yosemite, what seems to occur now is a grainy/garbled sound that seems a bit like the wrong format is being played even when 44.1KHz is selected in Audio MIDI setup and a 44.1KHz file is played in iTunes or in Safari.