Family dispute: Preamp to Eqaulizer wiring (Balanced or Unbalanced?)

I see no advantage to using balanced on one end and unbalanced on the other, but I don't think it's bad. Just clunky (due to the bigger XLR connector). If it was me, I would use RCA on both ends.

If it's a "stereo" EQ's, you only need one when using two channels.

His channel connections CORRECT, however he should be using the unbalanced connections on both devices. His connection is using the differential inputs and connecting to a ground referenced signal output. The impedances and signal grounds should match. Leaving half a differential input floating is NOT the way to go.

+1 this is the answer

As soon as a balanced connection is coupled to an unbalanced line the line becomes unbalanced and all the benefits of a balanced line are compromised.

If you had a T-R-S connection on both devices the circuit stays balanced.

I think you may be confused about what balanced means. This is not a completely correct description, but maybe it will help -- please forgive if I am talking beneath you.

Balanced implies a differential driver and receiver; you can think of it as having the positive and negative "sides" of the signal on separate wires with a third acting as the common-mode reference (ground, usually, when talking audio). In contrast, single-ended (unbalanced) circuits simply use a signal (positive) and return (ground) line. Balanced circuits offer greater noise rejection as any "ground" noise is coupled equally into both sides (signal + and -) and rejected by the receiver since it only "sees" the differential signal and not the (common-mode) ground noise.

A TRS connector can be used for balanced or unbalanced signals (it looks like a stereo plug). The Tip is usually (+), Ring is (-), and Shield is ground. If you plug a mono plug into a balanced input, the ring is often floating, which as Giz said means you have a floating input. That can cause noise problems.

There are all kinds of adapters for TRS to RCA in all quality ranges, but unless your components actually have balanced I/O there is no point in using any of them. I am guessing from you first picture that the NAD does not have balanced I/O, simply L/R inputs and outputs. That is not the same as balanced, and you don't (usually) create balanced signals from left and right channels.

HTH - Don

The sleeve of a TS/mono plug typically shorts TRS jack ring to sleeve, afaik, anyway. So, it would seem the inverted input (-) generally isn't floating, it's virtually always shorted to ground.

Not always, as I found out the hard way many years ago... Not all TS jacks are made the same.

This one seems to fan single outputs to feed two inputs, which is OK to do but unnecessary, and combine two outputs into single inputs, which is a bad practice.

Bob,

We're all guessing, since the labels are "Tape In" and "Tape Out", that black and red means left and right, not balanced.

I agree, little is absolute, but 99.975% of the time...

Yeah, well, one of the problem sets was from Neutrik, which caught me quite off-guard...

Most likely.

But my point is that running two outputs into a single input is a bad idea.

Perhaps the OP's dad is thinking that the "balanced" input connection means that L is on one phase pin and R is on the other phase pin.