What makes the biggest difference in sound quality?

Depends on what's the weakest link in a system and what it's replaced with

It will be great to hear what the OP reports back, and how it helps his/her system or not.

I am not even sure what components are in the OP’s system… maybe I lost track of it?

I am half-deaf, and wear aids to compensate.  Best $ spent, but was 'picky' as to how & with what...

Ignoring the 'cable conundrum' entirely, as my perception of late may hear the difference, but would chalk it up to a different system in a different space not 'lived with' long enough to ascertain a 'difference', however apparent to the host..

Believe that the space itself is ignored too often, but one needs to run what one has, to the 'best of...' what can be attained.

Day One; your space or mine:  "OK....sounds like....."

Day Two:  "Now I see what you're talking about..."

(One needs to adjust their 'onboard EQ'  to accommodate, but as to ones' preferences...we ARE from 'different planets', if not galaxies....)

...and it's Saturday 8, anyway.....*L*

I don’t have a problem with people that are half deaf and know it....

My problem is with people that are half deaf and DON'T know it, and then accuse others of being delusional.

I mean, I feel bad for them...it’s not easy to live with a compromised sense of hearing, but the sanctimonious attitude...that I can do completely do without.

@nickatnoon61  You do realize this is an audiophile forum, don’t you ?