You never know what today will bring

Huh? I thought that true balanced operation output is ALWAYS EXACTLY 6dB higher as the "equal" signal "halves" are summed, which is exactly +6dB, and has NOTHING to do with reduced noise due to common-mode rejection. Oh well, maybe I'm wrong here? Wouldn't be the first time....

From published measurements I have seen over the years, there is no 'exactly' or 'always' about these things. But we don't as yet know whether Judit's CDP is a true balanced design throughout, or just uses a splitter circuit to give a 'balanced' output. If it is truly balanced, than that will be the reference output level, and a single-ended output will be lower in level, maybe by closer to the 6dB figure than if it is not truly balanced (most CDP's are not). The common-mode noise rejection has mostly to do with the RFI/EMI picked up on the connecting cable. But I'm like you on these matters - definitely open to correction! The main thing is if Judit prefers the sound with the new connection.

The Electrocompaniet CDP is a true balanced design, as is the Pass Labs X-1 Pre that is next in the chain.

I have been swapping in new PCs as well. Since I do not have dedicated line I have a ground loop problem which I currently correct by floating all but one of my components. I have noted that polarity (which way I plug the floated PCs into their outlets) affects output SNR as well.

Balanced circuits are 6 dB or twice the voltage. Double the perceived loudness is 10 dB measured in SPL at the speaker.

Oddly enough, even Discovery Essence RCA interconnects seem to have a lower SNR (than other RCA interconnects) because I also tend to turn DOWN the volume knob a couple of notches when I use Essence RCA IC's between my CDP and pre-amp.

This is compared to other IC's such as Shunyata, Aries; Coincident, CTS; and HT, Truth Link. Go figure.