Maybe I'm misunderstanding something here, but are you guys getting 2.5mmTRRS to 3.5mm TRS adapters to convert balanced to single-ended?
Does it do this by summing the out-of-polarity (inverted) balanced signals together to form what would normally be the ground connector?
If so, I think that's a really bad idea. The output impedance of the amp---even at 3 Ohms---will look like a near short to the other amp.
At a minimum, the inverted amps will get hot from...