Balanced to unbalanced connections: a matter of the right connections!
My 6-channel level control for the Behringer DCX2496 described elsewhere uses a balanced output (via XLR) to connect the DCX to the power amps. This is in line with the stock unit; this equipment has been conceived originally for pro use where balanced/XLR is the norm.
Many people will want to use the (modified) DCX with power amps that have unbalanced, single ended inputs via high-quality RCA sockets. (Those RCA, or Cinch as they are also known, are officially called "IHF" sockets, but I'll stick to RCA for now).
Anyway, remember that the purpose of balanced interconnects is to balance the interference, noise, hum and buzz in the signal lines in order to cancel them out. (I'll just call it "noise" for short from now on). The purpose is NOT to balance the signals on each line! The receiver is supposed to act on the difference between the two signal lines and couldn't care less whether that was +3 and -2 or +2.2 and -2.8; in each case the effective input signal is 5V.
There's more detail about these issues here.
To get cancellation of the noise it is very important to have equal source impedances at the sending end of those balanced lines, and that is taken care of in the output stage of my DCX2496 6-channel level control. Equally important is that you shunt any ground noise current between two pieces of equipment away from the signal lines.
With a bit of care, you can connect a balanced output to an unbalanced input and preserve the noise-canceling properties of the connection. Using the cable shown below will do that.
Note that there are also XLR-to-RCA adapters available; I have some from Neutrik and they have the same connections, but I don't know if that is universally the case. In any case, if you use adapters, chose the ones that you can put on the input side (the power amp input), and NOT on the DCX output side! Then, run a standard balanced cable from the DCX to the adapter. The longer you can maintain the balanced connection, the better the noise canceling results.
