Console Insert to Balanced Line Input Conversion

A friend of mine wants me to convert a FOH board he owns for studio use. The main problem is the board has no line inputs... just mic. Someone jigged it up to use the insert return as an unbalanced line input, but the problem is he's running 100+ feet of cable and it's got all kinds of hash on it.

I suggested we add a transformer to the insert return thus resulting in a very nice balanced line input. One downside to this is the polarity flip is upstream of the insert, so it can't be used.

I had a spare Edcor WSM 10K:10K and wired one channel up last night as a test. It sounded great. No hum or buzz.

We're planning to do 24 channels, so I need to find a very good cost effective transformer. Edcor has two PCB mount transformer, one 0.25W and one 0.5W.

http://www.edcorusa.com/products/transformers/pc/pc10k-10k.html

http://www.edcorusa.com/products/transformers/pcw/pcw10k-10k.html

Check my math:
Assuming a 5V input with 1:1 ratio and 10K load:

I = V/R = 5V/10K = 0.5mA
P = VI = 5V*0.5mA = 2.5mW = 0.0025W

... so does anyone see a problem with me using the 0.25W transformer. They are only $6.12 a piece. Is there something I'm not considering here?

Thanks.