So I switched from XLR cables...


... to rca cables and my system sounds much better... 😳

it was a tad bright so I switched them out and everything smoothed out...

same brand etc.
128x128captbeaver

All true and valid points, Al. The balanced outputs in Tim de Paravicini’s EAR-Yoshino 868 pre-amp are created via output transformers (rather than integrated circuits or, heaven forbid, opamps)---which are widely used in recording studios, in which Tim does a lot of work. The pre-amp’s circuitry itself is single-ended.

And the balanced inputs in Roger Modjeski’s Music Reference RM-200 power amp are accomplished via some sort of resistor network, which Roger has described here on Audiogon. That description may as well have been, for a technically-limited music lover such as myself, in Greek. ;-) Unlike the EAR 868, the RM-200’s circuitry is fully balanced.

I'd like to introduce a new thought in addition to almarg's comments..  Even though capbeaver's XLR and RCA cables were made by same manufacture, there could be a significant difference between them.  Are the XLR/RCA cables the exact same model?  Or different models.  Maybe the XLR is silver/silver-plated wire and the RCA is copper?  Are the XLR silver-plated?  Maybe the RCA plugs are gold-plated (which would be a much warmer sound than the silver plated).  Also, many cable brands use a basic Neutrik XLR plug.  This can have a slightly dry/harsh sound because they use hollow/thin conductors.  The RCA plug could have a solid center-pin and conductor element, which could dampen the electrical resonance that shows up in the low mass Neutrik XLR.
From manual:

Balanced XLR Input Jacks
In most systems balanced XLR connections will give you the best sound. If your stereo preamplifier has balanced XLR output jacks, we recommend that you connect them to the A 21+ XLR inputs. Refer to the Balanced and Unbalanced Lines in the Technically Speaking section for additional information about why we recommend using balanced lines.

Note: Using balanced XLR input connectors results in a 6 dB higher volume level compared with using the RCA input jacks. This is a noticeable increase.

Unbalanced RCA Input Jacks
Use these inputs if your preamplifier doesn’t have balanced XLR output connections or if you simply prefer to use unbalanced connections.

Balanced/Unbalanced Selector Switch
Place the switch in the position for the input type you will be using.

Note: The Balanced/Unbalanced switch is not an input selector. Its function is to optimize the signal to noise ratio for each type of input. You should not connect both the Balanced and Unbalanced jacks at the same time with the expectation of switching between two different devices such as a preamp and surround processor.

Balanced XLR Pin Configuration

The A 21+ XLR jacks conform to the industry standard of:
Pin 1: Ground Pin 2: Positive (+) Pin 3: Negative (–).

Great Captain, the Parasound conforms to the AES standard. Now how ’bout the Mac?
balanced signals require both halves of the signal propagation to be exact and then electromagnetically and in voltage fields..interact and reflect off/in one another in perfect symmetry of their perfect signals.

Nice theory.

Reality says it has it’s limits.

It gets niggling little bits of it wrong. It is not possible to make it perfect enough for the theory to emerge as a reality. *

Problem being that it’s distortion components are the parts that the human ear uses for fine levels of discernment...

....which is the whole high end audio pursuit itself.

Both balanced and single ended RCA.... both being imperfect...as well as the rest of the system and the humans being imperfect (different hearing, different mind, etc)..combined with how the human ego/limits function in the meat box we call a human...those things all combine into, or emerge as - arguments among the meat boxes.

~~~~

* The Teo audio liquid metal has the ability to deal with physical perturbations and inconsistencies in construction..whereas frozen lattices of solid wire, due to how signal propagates in it..cannot. In this.. the problem with wire in balanced design..is pretty well wholly eliminated with the Teo Audio liquid metal conductor pathways. This point is utterly unique in electrical conductor design.