These are the perfect accessories for transparent, single-ended to balanced output conversion. They're in mint condition, and are designed to be ganged together for power, in this case with a very rarely offered Elpac 24V linear power supply for even better audio quality.
These were used by me with a mint Proceed AVP2+6, to create balanced outputs for my sub and surrounds. That prepro is also listed for sale, and these can be purchased with that unit or as standalones.
Asking $150, including USPS Priority Mail shipping and PayPal. The Elpac linear power supply is probably worth that much by itself! A 3rd FP-UBC2 converter is also available for purchase.
My veteran and perfect A'gon feedback allows you to buy with confidence.