I used the SACD and HD vinyl versions of Daft Punk's Random Access Memories to test.
I'm running cheap amazon XLR cables WBC Pro and a probably 20 year old chinese RCA cable I found in my basement in my setup, I'm comparing XLR to RCA output on the Envy with Immanis. I mention the cables to show that the playing field is level. Here's what I've been able to confirm;
XLR:
More Audiophile
Smaller stage, feels more natural and correct, notes are perceived as larger as a result
better separation in the stage, easier to pickout instruments in complex passages due to cleaner edges of notes and better separation
Tonally deeper sub bass and more discernible texture on bass notes
Drier sounding
Background minor rhythms are more apparent such as the guitar on Game of Love around 30s whereas with RCA that rhythm guitar part is there but
the rhythm is less apparent, it has to be looked for, probably due to better separation of XLR
RCA:
"Wet"/Liquid sounding, has some sort of "distortion"(not sure thats what it is) that sounds very very good, a flowy and slightly weighter liquid quality that I wish XLR had
Has bigger stage, sometimes sounds artificial, as if things are pushed away and almost becoming stretched as a result of notes at the periphery
More musical
Slightly more mid and sub bass quantity but less audible than felt due to poorer separation in-stage, XLR bass guitars and more discernible due to better separation in stage even though less impactful and less note weight
RCA is a simpler connection, additional processing must be done for XLR and Envy isn't balanced on XLR. I wanted to compare the two, at times I prefer XLR but most of the time I prefer the LIQUID quality RCA and the expense of slightly poorer separation and congestion in stage. I wanted to do this cheap test before buying expensive RCA or XLR cables. Maybe an expensive RCA cable could keep the liquid quality I'm hearing with RCA but add the better separation I'm hearing with XLR.
Open to suggestions on RCA and XLR, probably looking for something pure silver, was considering DHC Prion 4. Not 100% convinced which way to go yet but leaning toward a LOW DCR RCA cable.
I had my girlfriend to some of the testing, flip the switch between inputs on the Envy, I was able to tell the dfiference between XLR and RCA easily and correctly. The most noticeable tell being the liquid RCA vs the drier but more audiophile-ish XLR.
@Doug2507
FWIIW I have my envy volume set to 12 o clock and my DAVE with blu2 between -22 and -18 with my different HP's
Because I have analog volume control on my DAC(it's called variable setting), what I've done is set my DAC volume to the lowest level that allows me to keep the Envy potentmeter on max volume all the time with me having it at the perfect db level I want from Immanis. Sometimes when I change albums I have to pause the music and lower or raise the DAC volume a few points. IDK what voltage output I'm running but operating in this level (unity gain) provides me superb sound quality. I am experimenting now between the 0db, 3db and 6db fixed settings vs the variable setting-doing a comparison to see which has better sound quality. Bear in mind the 13.5V rms variable measurement is for MAX, I'm not running the DAC at max on variable I'm running it as low as possible as to give me perfect volume with envy on max. IDK what the V rms is currently, I'll ask the DAC designer if he has an ouput chart for the variable setting, I'm at abuot setting 110 in most case, it works on individual clicks up example 111, 112, etc. I would imagine thats increasing voltage in very small increments, theoretically opearating at the lowest vol level should be best.