Originally Posted by vowel
I have a small home studio with some nice gear.
I have a patchbay which I have set up.
I have a mixture of balanced and unbalanced gear which I have plugged into the back. The patch cables are balanced (I think) and it is all connected to an MBox 2 pro and I can't hear any problems.
Am I being naive or should I being doing something else to optimize my setup.
Impedances, resistance and the like confuse me - so do you think I'm ok if I can't hear any noise/problems?
The choice between balanced and unbalanced connection methods (eg grounded or floated -ve) is not just a question of impedance or resistance, but is dictated by circuit topologies.
In general, gear that has transformer balanced outputs needs to have the -ve grounded and/or the screen floated, whereas gear that has active (op-amp driven) balanced outputs generally needs a floated -ve when going to unbal. That's regardless of the question of level matching (eg you may also need to pad 10dB or more to bring a +4dBu signal down within the headroom limits of most -10dBv unbal inputs).
Conversely, when going from unbal to bal it's usually okay to connect the input -ve to the shield (but you may need a line driver to step up the levels and match the impedance to drive a +4dBu low impedance input).
It's not only a question of noise or other obvious/audible issues - although that's certainly a concern. Active balanced outputs don't generally like to be grounded on one side (pulls the power rails down as well as generating a fair bit of heat in the circuit/chips). So you should really check the documentation for each unit to see how it should be wired into your particular setup.
If you're correct that the patch bay is balanced, then you should probably look at anywhere you are patching into gear that has unbalanced inputs, to make sure that the output stage of the gear that will be patched in is compliant with the way you have it wired (which is probably defaulting to -ve to ground at present).