So I switched from XLR cables...

Hi,
if your equipment is balanced from input to output then XLR will most probably sound better, as it will have less noise and more dynamics. 
XLR connection does not translate to fully balanced design.

Mac 41 pre into new A21 Parasound ... balanced to balanced

im a tweeker so more to come BUT the rca’s smoked the xlr

@captbeaver, have you verified that both the Mac and the Parasound (and your XLR cables) are wired in accordance with AES File 48? That is, Pin 1 is Ground, Pin 2 is Non-Inverted Signal, Pin 3 is Inverted Signal. As Ralph Karsten of Atma-Sphere has stated here dozens of times, it is only when all XLR connections are wired in accordance that you hear the benefits provided by true balanced signal transmission.

Parasound amps are NOT balanced, they use IC conversions on the inputs. The JC1 or JC5 might be different but generally most of them are not differential balanced.

Comments WRT Prior posts above

(A) ....Mac 41 pre into new A21 Parasound ... balanced to balanced...I’m a tweeker so more to come BUT the rca’s smoked the xlr....

(B) ....XLR sounds better than RCA in my system. If your system isn’t fully balanced XLR may not work for you. .

MY TAKE: the differing opinions support my experiences that it is ENTIRELY system dependent ..,,full stop.

Why?

(1) A mag review of that PARASOUND amp states that it is not advised to use both the balanced and unbalanced inputs at the same time, which is cumbersome ( at a minimum...) in many systems. The new Parasound Halo P6 preamp was recommended as a proper stablemate to solve this issue. I don’t own it, but my read is that possibly mixing them up with mixed brands might introduce some compromises.

(2) Some systems manuals DIRECTLY suggest the mfg. XLR preferred pathway to audio OZ. For example, my REGA OSIRIS integrated amp and its stablemate REGA VALVE ISIS cdp/DAC manuals (and dealers ...) both specifically recommend using balanced interconnects instead of RCAs. In a length comparative shootout of ICs in > $1000 range,

(I) both the dealer and OEM manual recommendations were confirmed to me in spades.
(Ii) the actual selection of cables also do matter. NORDOST FREY XLRs bested all the half dozen plus contenders and pretenders in the $1000 - $1500 price point strata in my system. As a side note, all the brands bested the $200-$700 options fwiw.