Dedicated 20 amp lines/should i use a sub panel

@almarg @jea48 there are othres also...
A little assistance, please?

I will be running 3 lines all identical in length to avoid ground loop hum, my interest is will there be any difference... negative or positive...from running a sub panel as opposed to just using open spots in the 200 amp panel. the closest and farthest line will each power a REL G1 sub and the centre line will power a Synergistic Research powercell 10 UEF, which is where my  tube cd, tube pre and ss amp are plugged into. this is how my system is presently powered just not with dedicated lines.

Thank you, Larry (lak). Jim (Jea48) is the expert when it comes to electrician-type matters, and hopefully he’ll chime in. But FWIW I agree with all of the comments by Dill. I doubt that adding a sub-panel would provide any benefit, and as Dill indicated inserting additional contacts into the path won’t be helpful.

Unless, that is, the sub-panel is something like those made by Equi=Tech which incorporate a high quality transformer and would provide balanced power to the system. However their models cost in the vicinity of $10K or more, and weigh upwards of 300 pounds.

Good luck. Regards,
-- Al

Jim, Some replies below.

By side by side, do you mean the breakers are installed directly across from one another? Connected to the same main bus breaker tie. (Both are fed from the same leg, Line.) Or, do you mean one is installed above the other, side by side? One fed from leg, Line 1 and the other fed from Leg, Line 2?
>>> Same leg/busbar. One 20A breaker above other.

Did you use Romex?
>>> Yes. 8/2 NM-B (not 10 as I said before) cable from Lowes.

Did you try to keep the 2 cables separated from one another at least 6" after getting them out of the electrical panel, as soon as practical? Especially a long parallel run?
>>>Yes. 12 feet apart.

Is it possible one of the 2 is running parallel next to some other branch circuit?
>>>It’s possible but not obvious.

>>>I also tried tying the ground wires to the same terminal, removing the ground (to test only) and moving other equipment to different runs to no avail. I’ll be honest, I abandoned messing around with it after an hour and removed one leg and used the cable for another project. The one 8/2 run on a 20A breaker into a 20A L5-20/L5-20P receptacle/plug sounds great.