I have a spare pair of matching cables, 6 nines copper, locking RCA's both ends. they sound terrific now.
I'm gonna change the connectors on one end to XLR female, leaving locking RCA's on the other end. I've got some Cardas silver solder.
That will give me direct comparisons: two pairs of identical cable construction and length, only variable: xlr or rca out.
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noise
happily, my entire system is dead quiet, tubes and all, pleasantly surprised every time I turn it on. bought used mx110z had a very slight hum when volume was juiced past half (more than needed, but still ....). Gone after Audio Classics overhauled it.
Prior McIntosh SS Preamp C28 had a slight hum. McIntosh overhauled it, declared it up to specs, came back still very slight hum using low level inputs only. I changed the ground connection inside, gone. Sold it to get back to tubes.
Occasionally I hear a very faint hum, oh no, then I realize I left a fluorescent light fixture on, it's expensive high class noise free ballast has a very faint hum. OFF, gone. Whew!
My closest audiophile friend with a wonderful sounding system lives with tube amps with a slight hum. I've offered to go thru and isolate the source, but he has lived with slight hum, had them fixed by the maker, ok for a short time, it came back. I couldn't live like that. My old Fisher Mono Blocks, 80z made it 1958, are dead quiet. I used to forget to turn them off frequently.
I've never had any noise except many years ago, when listening to Onkyo's 1st receiver with TV band tuner, it picked up a CB radio occasionally. Problem went away by itself, perhaps someone moved. And recent tonearm, exposed silk covered litz wire got worn to bare wire, a faint buzz, killed it with new wire.