How do you know when a stereo sounds good?

I used acoustic devices instead because i dont have any other means ...

I am satisfied....Acoustic is underestimated...But someone can use the two for sure.... Passive material treatment and DSP...

I use also a homemade mechanical equalizer inspired by Helmholtz resonators and diffusers....I am satisfied with these 40 and more grid of resonators and diffusers.... Location is the crux and fine tuning....According Hass law i directed the wavefrontd asymmetrically modifying it with different pressure zones with some resonators located around each speakers...My S.Q. satisfy me ....Nothing very costly even better will convince me to upgrade because when we listened music with a smile we are there...

For me the goal is to appreciate music and all acoustical cues coming from each recording....

When all albums are interesting acoustically even the less well recorded YOU ARE THERE...

My system value is under 500 bucks and is not the best at all but is  one of the best quality /price ratio...

Controlling vibrations, decreasing the electrical noise floor and passive material treatment and especially mechanical acoustical equalization of the room in relatiuon to the speakers was my way...

i would be very curious to listen to your systrem...

my best to you....

Here is the crux, everything, including my turntable goes through DSP.

@winnardt I could, but I tried and I have a day job so I'm tired of trying. Now that will be my last word on this topic. 

@aewarren

"When Adele becomes listenable. (It hasn’t happened yet but that’s my ultimate goal)"

In other words, it ain’t happening!

For me : Adele = inhuman sonic Hell.

It’s as if I’ve become afflicted with some terrible sonic disorder that plays havok with my sense of timing.

Can be a most unsettling, if not a downright terrifying experience.