xlr vs rca

I’ve found it’s very often advantageous to float the ground at one end of the signal path.

Agreed that is often the first thing to try out....it stops the microamp ground loop currents flowing between the various chassis as well as still grounding the shield to give you better RF protection.

Balanced circuits are better at rejecting any noise from the power supply but your description of it doesn't make any sense. It isn't a ground loop problem.

You need to read up on what Whitlock says about the reasons why XLR balanced is so important for ground loops. Think about how a power supply fluctuates under heavy demand and how this may affect microampere ground loops between gear (the BIGGEST problem in audio as RF noise pick up on analog audio is much less common). Then realize that ONLY ONE wire in in an RCA circuit will carry this current flow on your signal wires - IT CANNOT CANCEL (as it does in well built XLR gear and cabling).

=> this is why a BIG BEEFY power supply is NOT simply about more power...often it can be more important for how much cleaner the backgroud or canvas upon which the music plays can become...

Perhaps I was not clear in the last post.....a BIG BEEFY power supply means less fluctuations due too the varying demand from dynamic music and therefore less ground loops from leakage to ground from the PS => less noise induced into the low level analog signals between components.

If you care to be more specific about where he states this I would be happy to read it, but the link you gave has 10 papers on it and I don't care to read all of them trying to find it.

Herman, I have never seen a tube preamp or amp that achieves balanced operation using completely discrete amplification for the plus and minus halves of the signal. I wondered if you had, and I guess not. BAT most certainly does balanced operation the same way Atma-sphere does. I think to do balanced operation without the differential topology would be a disaster because of the difficulty matching Rp, mu, and Gm for two completely disconnected sets of tubes. At least in differential topology the current can be held constant for the two halves of the circuit by using a CCS in the cathode of the dual-diff amplifier, and the current on one side will go down by the exact complement of the increase in current on the upgoing side. The only place I have seen balanced without differential is in the context of using an IC or a 2-section bipolar transistor, which can have incredibly closely matched sections.

Yes, I know an MC cartridge is an inherently balanced signal generator if hooked up to a balanced input. I guess I was thinking of a single-ended signal from a cdp or other source.

I understand the use of the CCS but I don't see where this makes the circuit immune to differences in the tubes. It's been awhile since I've studied them but as I recall any difference in the components will be reflected in the output.