And the biggest influence on sound quality is...

These days, I find myself focusing on well recorded music. With access to so much content, why waste time trying to make a turd sound good.

Room 1st which includes dimensions and treatments.

system synergy 2nd - from cables to matching amp to speakers.

3rd is speakers sized for the room. You don’t want small monitors in a 30’ room and you don’t want large Wilson’s in a 10x10’ room. I had large speakers in a dedicated room within a room 27’ long with 15’ ceilings. I moved to a smaller house and tried the same speakers in a 16’’ long room with 8’ ceilings, great speakers in a large room to terrible sounding in a much smaller room. 
 

Right behind the speakers are the amps/dac/preamp all spec’d according to the value of the speakers. Your not going to spend $2000 on an amp if you have $100,000 speakers and you wouldn’t be spending $100,000 on an amp and dac if your speakers cost $3500.

Ultimately, recording quality and room will define the limits, but I am talking about top level equipment. In your average $50k system I am not sure which component contributes most. But I belong more to source first school, so, I guess, it's either the recording or "transport", be it turntable itself, cd transport or tape deck transport. Poor recording will sound like junk anywhere but with average recording the better your set up is the better it will sound. It's a continuum from very poor to great recordings, and I think the answer to the question is more complicated than this or that.

My ears. Have fun with it all and the experience.

The room and the system are what they are, recording quality easily the greatest variable. Now, one  can manipulate and change audio components and room treatments, same doesn't hold true for any particular recording.