Poll: Most impactful component

Oh good. It didn't seem like something that you would say, which is why I was surprised. My apologies.

For varying reasons,  I toggle back and forth between a PrimaLuna integrated and Pass amp/Cary preamp combo.  I also recently upgraded from a NODE/Qutest (w/ SBoosters) combo to an Innuos Mini/PSAudio combo.  Zu speakers are the constant.  Nordost cables.  Stream exclusively.   No question that the Pass/Cary/Innuos/PSA combo delivers the best listening experience to my ears.  That's not answering your question other than to suggest the obvious that it all matters.  If I had to pick, though, I think the streamer upgrade made the biggest difference in my modest system.

which component has the most potential to improve a stereo system?

I think it depends on system deficiencies.

I have B&W 804`s teamed up with an Acurus A-150 power amp. (a BIG no-no!).

 In order to rectify the harshness in the upper frequincies, I inserted a tubed preamp into the system. I `ve taken a sows ear and made it into a silk purse.

Generally speaking I think it`s the preamp, and/or a DAC.

1. Room

2. Speaker position

3. Everything else