everything sounded great until the upgrade

There has been an evolution, among the majority of brands, toward more and more “detailed” sound that means a leaner sound with less upper bass (that bass obscures higher frequency detail).  It seems to be what most buyers want.  If you are in the minority, you have to either look for vintage gear or the brands serving outliers.  I happen to like a warmer sound, which is why I favor low-powered tube gear from certain brands, such as Audio Note and Synthesis, and solid state from the likes of First Watt.

If you have changed the balance of your system, you can try to compensate by doing simple things, like experimenting with speaker or listening chair placement, minor acoustic treatment, like putting tapestries on the walls or using an area rug on the floor (things that may not cost much or unduly disrupt your life).  Doing more to compensate, like buying different cables is a gamble because it may not work.  I hope it is something like changing the toe-in of the speakers that will do the trick.

sometimes just getting familiar with the new sound will also change your mind, so be patient and go slow with the changes.

I can understand your not wanting to fully disclose the products involved, but perhaps you can say what were the components that you liked before the change.