I've recently purchased an Edirol UA-4FX usb sound mixer, which is supported in a "standard" usb sound device mode which supports 16bit at 44.1Khz., and an "advanced" mode which allows up to 24bit at 96Khz as well as enabling use of the onboard midi ports. Alsa supports both the standard and advanced modes on this device, however, when I am in advanced mode, I am getting some extra background noise which is especially noticable at lower volumes and certain frequencies. I have attached a tar file containing two mp3s comparing the output of the standard and advanced modes. I've tried linux kernels 2.6.28, 2.6.29, and the git sources alsa code all with the same results. Is anyone else with this device having a similar issue?
Note: the file was too big to attach, so here's some urls for each: