So this is my mixamp hooked up to my mstage.
Here's how I have it setup:
Xbox/PS3/PC -> HDMI cables -> HDMI Splitter -> Harman Kardon AVR-247 -> Optical passthru -> Mixamp -> Startech HeadSET splitter -> 3.5mm stereo to 2x RCA -> mstage -> headphones
When I don't need chat when I'm playing consoles, I just plug my headphones directly into the receiver. When I'm playing PC games or just want to listen to music I have an Asus U1 hooked up to the mstage to supply it with DH. Then I have some Monitor Audio speakers and a carver sub set up for when volume is of no concern.
So do you have a 1/8" mini to RCA adapter from the Mixamp to the M-Stage?