Balanced DIY Pass Amps

Hi, all,
I've built a few pre-amps and headphone amps now and think I am ready to try a power amp. BUT...I need something with balanced inputs (due to the noisy environment in which I live and the long cables, 50 ft, between pre and power). I'd prefer something Pass. Suggestions?
TIA,
Riki

Aleph J, your best option. Board and all the parts are available.

F1/F1J, but the semis are not available, board available from csample (Chas).