OK, pretty much set up exactly as yours (i dont have filters).
Still getting lots (interference lots) on the 2nd channel.
I've taken the pre-amp down and used a short cable to play with it at a lower level.
The specs say to use "normal cat cable" - is normal 1-1, 2-2, 3-3, 4-4, 5-5, 6-6, 7-7, 8-8?
Using a ethernet cable tester, all pins are reading OK. It's certainly not cross over.
Thats what i have got in use(shielded).
When i use my damp finger to initiate a pulse on each channel, i get a pulse between the - and gnd, (not + and -).
I get a red LED up on the board, so i can assume the power is getting through on the right cable pin ok.
I'm off for a sleep, i'll be back on this later tonight/tomorrow now.