Why does my system sound better??

I agree with Phd,

I think the answer here might be that after components are on for a while, the circuits stabilize, they reach their optimum operating temperature & the sound will usually change for the better, could be for the worse. It may be you like the sound better before this happens!

My second best guess is the listener has not acclimated themselves to the "flaws" of the most recently attached speaker until some time passes. All speakers have a personality and none are without flaws.

I assume you had two beers in the process of testing speakers. By the second beer, your blood vessels in your ears opened to their fullest, allowing you to truly hear the speakers for the first time! Did you happen to dim the lights, or have a girl in the room with you. All audiophiles know these factors weigh heavily on the sonic character of the equipment.

1. Placement has a _huge_ effect on what you hear. Inches matter. If you didn't mark your old speaker location with tape, match up the spike holes, etc. they're in a different location.

2. Your hearing adjusts to consider what it hears on a regular basis as "accurate." Without listening to enough live music "accurate" isn't. Changes from this can be good or bad.

3. Expectation bias could have changed your impression of your new speakers.

I used to leave my pretty good system on all the time because it always sounded better after an 1 hour or so of warm up.

After some years had passed the system seemed less pleasing I did all kinds of tests and just shut it off one day in frustration.

I now know that my particular amp sounds best when a little warmed up but begins to sound coarse after 4 hours or so (yes it runs very hot, always has).

I have contacted the manufaturer who says he has never experienced this and would be happy to look at the amp. Its about 90 lbs and needs to ship to the opposite coast so I'll wait until things get worse.

For now, I turn it on when I wnt to listen and shut it off afterwards.