If it is solid state amp leave it on for a week or two, listen to it or not, at the end of the 2 weeks, if you don't like it sell it and get something else. Don't try to make gear sound how you like it, buy gear and keep gear YOU think sounds good.
everything sounded great until the upgrade
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
Any other options? I could upgrade my speakers but I have no budget for that.
2. I could sell the speakers and use money to buy used ones that go with the amp.
3. Lastly I could change the source, but was it the culprit - to begin with?
btw - the sound of the "new" amp is decent with my turntable, and terrible with my CD player.
(If I wrote brands and models it would throw the discussion into "A sucks, B is great")