The I2S pads come more or less directly from the empeg's DSP chip, so that would be AFTER pretty much everything has been done to the audio. I haven't tried it yet, but all of the adjustments should "just work" through I2S.

However.. it is not entirely clear to me whether the I2S outputs use 5V or 3.3V. The datasheet for the DSP seems to indicate 3.3V, but I'd like to see it on an Oscilloscope just to confirm. Stu would already know this too, so if he chimes in..

EDIT: The schematic indicates 3V on the IIS header, so it should be good.

That's important, because 5V could fry the BT module. So you really want 3.3V logic there. Easy to convert 5V to 3.3V with a 10Kohm and 20Kohm resistor ladder, if it is needed.

Cheers