everything sounded great until the upgrade

You don't say what amp. you have so it is difficult to comment. Have you somehow changed a "gain" setting somewhere in your system that could be affecting how aggressive and unpleasant it now sounds? 

It appears you liked the sound of your previous amp.  Perhaps sell the amp and replace your CD player with a really nice streamer.  I have an OPPO 105 and no longer use it.  Who wants to get up to change a CD?  I like also my huge library and easy access using Tidal.

Let the new amp break in, sometimes it takes weeks. Never turn it off.

Try an outboard DAC with a tube output buffer.

My Amp doesn't even have an on/off, switch,same said for my pre-amp and Phono amp.

Turing your gear off and on just kills it's life span and doesn't help the sound. I work in broadcast with gear costing  thousands and thousands and thousands of dollars and it all stays on till it fails.

Give it time, you could end up all right.

There are also a ton of inexpensive tweaks that can make a huge difference too. 

Just putting 4 McCormack Tip Toes under my old Conrad Johnson turned  a very good amp into a sumptuous sounding piece of gear.

HiFI tuning / Synergistic fuse to replace the main power fuse, better power cord and AC outlet ( even just Green Dot hospital grade AC cord/outlet) etc are all reasonably priced add on's that can make a big difference.

Don't chuck the amp out yet.

Hope some of these things will help!

@grossman616 

Yes! Very helpful! However, should I really not turn it off? Ever? Doesn't it wear it out?

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.