If the amp has TRS and XLR inputs, one for left and one for right, then those are both balanced inputs. Both the audio 2 & 4 have unbalance outputs.
Now if the amp has TS and XLR inputs, then the TS is unbalanced, and the XLR is balanced. If this is the case then you can use something like this...
http://rsk.imageg.net/graphics/produ...160364w345.jpg
http://www.radioshack.com/product/in...ductId=2062455
And you can just hook one up to each rca on your main out, and plug them into the amp.
Now if that's not the case and the inputs are TRS & XLR. Then you'll need a Direct Interface Box (DI box) adapter, to convert the unbalanced signal to a balanced one.
Since you're using 2 channels (L&R) i would recommend something like this...
http://img3.musiciansfriend.com/dbas...8/9/240689.jpg
http://pro-audio.musiciansfriend.com...ter?sku=182481
Then you'll still need the rca-to-ts adapters above, and you'll need 2 xlr cables to connect the box to the amp. Set the attenuator to 0db, the mode to 2-Ch, the ground to Lift, and you'll need a 9v battery turned on.
This box converts 2 unbalanced inputs into 2 balanced.
Since you said the amp has XLR & TRS, this really makes me wonder. Not many amps have both, since they are both balanced, and TRS is usually used for a stereo unbalance signal in amps. I'm thinking that the amp has XRS & TS. Which means you'll only need the RCA-to-1/4"TS adapters.
On this forum, i've found it's pretty common for people to confuse TRS and TS since the inputs look very similar. The difference is the number of wires in each cable. You can see in these connectors...
http://t2.gstatic.com/images?q=tbn:A...3NUU7gSvKq1SDg
A TS cable is used for one thing, to send a unbalanced mono signal.
Now a TRS has posible 2 uses, to send an unbalanced stereo signal, or to send a balanced mono signal.
I hope this helps you out.