How many dedicated lines?

Just for the record: (1) My sub-main box is also grounded back to the main. (2) What Liguy calls an isolated ground is not isolated in my system, it is a secondary ground and is totally acceptable to Oregon electrical code.

Also, just for the heckuva it, I disconnected the secondary ground (the one from the submain) and it made no difference either musically or to amplifier hum-- this indicates to me me that the main (house) ground is good, and there is no safety issue involved.

I actually would not have needed to put in a sub-main ground, but it seemed like a good idea at the time, and was not expensive. In fact I got that ground info. from an Agon thread of long ago. Cheers. Craig

Thanks to everyone for your excellent input and advice. One more question--someone told me that when running multiple lines out of the box you need to run them all from either odd or even outputs (2,4,6 or 1,3,5 etc.) in order to avoid phase problems (I hope I'm explaining this right). Can anyone verify that?

Yes that is correct & it's another good point! All the evens are on one of your 120V phases and all the odds are on the opposite phase. Best to use the same side for everything, hopefully most all the noisy loads in your house are wired on the opposite phase, or can be rewired that way (I did that). Don't unbalance your transformer's loading too much though.

Craig, I was referring to Bob's recommendation to have an isolated ground which is not to code.

Read again: "consider isolated grounding". I am not recommending it, but many users do so from experience so I just threw that in. However think about what is your objective? Are you more intersted in good sound or in meeting code? Poor analogy: When I'm in a hurry to get somewhere, the last thing I worry about is obeying "the rules" (speed laws)