Forgot to mention. I cannot decide which one I like better yet. Sound is just vastly "different"
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I think that a contributing factor to the differences you heard might have been the effects of connecting both sets of outputs of the player to the Theta at the same time, particularly if the player provides signals to both its xlr and rca connectors simultaneously.
First, crosstalk between the two sets of signals may have been occurring. Second, if, as is sometimes the case, the player's rca outputs are driven by the same output stage that drives one of the two xlr polarities, the Theta's 10K input impedance might have been low enough to significantly unbalance both the amplitudes and the impedance levels of the balanced signal pair.
It's also conceivable that some fraction of the signal return currents for the rca connections might take a path through the grounds provided by the xlr connections, and vice versa, affecting low level noise (which can affect ambience perception) and/or crosstalk.
And are you certain that volume levels were precisely equalized during your comparisons?
On the other hand, if you were to just connect one set of cables at a time, you would be faced with the issue of assuring that the equipment was in an equal state of warmup during each part of the comparison, as well as the possibility of aural recollection perhaps becoming less precise.
Getting meaningful and reliable results from this kind of comparison is not necessarily straightforward.
I connected the XLR and the RCA's to completely separated inputs on the Theta Preamp, and then matched volume levels using an offset. The Marantz source has completely separate circuitry for the 2 channel balanced outputs than for the 2 channel RCA (which are part of the multi channel set of outputs). All I need to do for A/B comparison is switch between inputs on my preamp with the remote.
Thanks, George. Edorr, a quick experiment that I think would be worth doing would be to see if you hear anything when you select the rca path while the xlr connection is present but the rca connection is not, and vice versa.
Any low level crosstalk that is not precisely in phase with the signal it is coupling onto would certainly figure to affect image focus.
Always compare XLR to RCA of same model IC if possible.
I don't recall any brand/model of IC that I have used where the sound was absolutely identical between RCA/XLR, even though I have used some very high end cables. The similarity between the two when compared to an entirely different brand/model is easily heard, but there is a distinction between them.
I have found that typically every cable and every connection makes a sonic difference.
Many components sport XLR (balanced) inputs and outputs without really being a balanced circuit to impress their buyers. True balanced, from input from a cartridge to the output of the amp will reveal a much better signal to noise ration, and better sound. True balanced requires a separate circuit for the + and - portions of the signal...therefore they are about twice as expensive to produce.
I repeated the expiriment, but now instead of running the multi channel preamp through the single ended HT bypass of my 2 channel preamp, I hooked up the balanced outputs of MCH preamp directly to my poweramp. So now I was comparing fully balanced source + preamp + poweramp with single ended though the same components. No contest. Balanced wins hands down. More "weight / body" to the sound.