The DSP (CPU) is propably TMS320VC5409:trevmar wrote:H2 HARDWARE DETAILS
The CPU is a TI320 VC509A. There is no clock Xtal trimmer, so your recorded data will always be a little bit deviant from an accurate timeline.
Too bad it's serial port doesn't support I2S, if it did support it then we could put a S/PDIF receiver chip there to bypass the A/D.
I think the noise comes from DC/DC (up-)converter mostly (in addition to EMI from CPU and various signals on PCB). Don't know if it is bypassed when you use the 9VDC input or not, but it would be nice to test the noise level with an external 9V battery vs. internal 2x AA batteries.