everything sounded great until the upgrade

Very simple, stick to what works. If possible go back to the original amp. The new amp purchase is a mistake. You will be throwing good money after bad replacing everything else including speakers to match the new amp purchase. Why can't you sell the new amp? Do you still have the old amp?  If not, this is typically the price paid for "not" leaving well enough alone. We all have been there.

@thehorn 

that's my biggest lesson from it: it's starts with the amp.

I always chased the speakers before.

If I had the money and time, I'd buy a different system for my 10 favorite songs each because they all sound different now

grislybutter,

"that’s my biggest lesson from it: it’s starts with the amp". I never said that Gris, it starts with the source (turntable/cartridge/tonearm, or Cd, etc), and the quality of the actual recording process on the format. It’s quality in, quality out, or, garbage in ...... etc.

Now your narrative implies that you have a good turntable, (get it isolated!!!), and you have the M/F A3.2, so optimize your speaker set-up as I & others in this form have suggested, then enjoy the life long learning curve.

When I was 20 I bought an Oracle Delphi turntable, with a Syrinx LE1 arm & a Grace F9 cartridge. In the subsequent 43 years tonearms, cartridges, pre-amps, amps, speakers, "houses", have all come and gone. But the one reference piece that’s remained, the foundation I could measure all other components against, was my source. That in my experience is where Phile’s with limited resouces should start. The source.

So don’t ignore your room, book cases, curtains, crown molding, pictures & end tables maynot be as effective as dedicated defusers/traps, but hey. This is your home, not a lab. Lets not lose perspective, are you spinning a few tunes, or are you finding a cure for cancer?

 

 

In short: I loved the sound of my modest system, until I upgraded my amp. Now it sounds pretty horrible. It went from a warm sweet embracing easy-to-listen sound to knives and forks trying to escape from a bathtub.

So...

1. I can just unplug this new amp (used) and sell it

If you changed the amp and it is bad now, then I cannot see why people are talking about sources, DACs, TT, the room, cables, etc.

IMO… Sell that amp and move on… or back to what you had.
(The only thing you changed was the amp right?)

With respect to warm up times, I plugged in a used phono amp which traveled 1/2 way around the world. After the 90 seconds, when the LED when from yellow to green, it sounded pretty good.
I turned it off, waited a couple of minutes, and then pulled the cover off to flip switches for the cart I am running. Another 90 second of power and it was even better.

If it sounds bad at the first 2 minutes, then 2 hours or 2 days may not help it a lot.