Well, you're welcome but now I'm confused.
Each TRS input is a mono (although balanced) signal. (well, it SHOULD be) You cannot put a stereo signal into that input (well, you CAN obviously as the jack is technically a "stereo" 1/4 inch jack). A balanced audio signal is audio, but has a 'hot' or positive element (I call it the push) and a negative element (I call the pull). The third pin is sometimes
connected to the cable shield, and sometimes not (and sometimes at one end but not the other). XLR connections are the equivalent to a holy war...
Anyway, the TRS jack wants either
an XLR balanced signal OR a 1/4" stereo jack that is wired LIKE an XLR
and NOT wired with a stereo signal
. (again, this is why I hate, no, DESPISE
these connections). The have one area where they are of value, and that is on the back of a fixed, large mixing console due to smaller footprint. Otherwise, I think they are horrible!
Now, you might be able to 'cheat' a bit if you take your RCA signal and attach it to the stereo jack as follows:
PIN of RCA to TIP of Stereo 1/4"
RING of RCA to center band of stereo 1/4"
DO NOT connect to shield (top band) of 1/4" stereo jack
I think that will work, but the signal will likely be low. Make sure the 'pad' is off with my suggested trial.
Finally, I would contact M-Audio to get there suggested connection schemes. They designed the damn thing, s they should be able to direct you to the best way to connect it.