Audiostix2 modifications

Component interference problem
The gpsstix (and hence the audiostix2) has a component interference problem which can be seen in this photo (note that the gumstix and gpsstix boards are not parallel):

This is caused by capacitor C203 on the audiostix2 board coming in contact with the processor on the gumstix board. The gumstix board in question is one of the first XM versions (but before the J fab). The gumstix board also had the 32 kHz crystal replaced, as shown on the gumstix modifications page.

I found that by moving the capacitor over slightly:

I could get the boards to fit together like this:

Note: if you have a gumstix with the larger 32 kHz crystal, then I'm not sure if moving the capacitor like I did will help (since I think that the capacitor would then hit the crystal, but I don't have an older gumstix to test this with.

Also visible in the photo (showing the relocated capacitor) is a 10k pullup resistor between The RxD and Vcc pins on the FF-UART connector), which is required if your gumstix is a pre-J fab, and you want to boot with no tweener or other serial device attached.

Other Modifications
Isolating USB from VBatt on Audiostix2 or Breakoutgs

In brief: If you want to use the USB port while powering the device from the V_Batt power jack, remove ferrite bead FB4.