I've got Stu's S/PDIF digital out card running to a modified DAC next to the amps in the trunk of my car. MP3's sound great! All noise and ground loop problems completely eliminated.

However, Stu's card doesn't support analog aux in, so I lost XM radio. No big deal, fidelity was horrible on the XM digital -> DAC -> ground loop isolator -> ADC -> empeg path. But now I have to rig up a digital XM input!

My current plan involves tapping into an I2S stream in my Delphi XM receiver, buffering and routing it to the second empeg DSP I2S input.

Since I'm willing to give up analog aux in, hopefully I don't need to change much software. I just need to have the DSP select a different input when "aux" is selected.

After a quick browse of the hijack code, it appears I can modify empeg_mixer.c function empeg_mixer_select_input to program the DSP to select the CD2 I2S input. I will change the aux_setup record to be almost identical to the mpeg_setup record except for selecting CD2 instead of CD1 (bits 5 and 6 of HOST register 0xff9).

Any other things I should consider? Comments would be much appreciated.

Thanks,
Jon

I know Stu was tossing around the idea for a digital input at some point. You may want to ask him how far he got with it.

I've been bugging Stu for a while now about a digital input, but he's been too busy.

Plus I don't really need a full S/PDIF or TOSlink input... just need to route the raw I2S from XM's STA450A to the empeg DSP.