PS Audio Power Plant 15........

To the OP,  If you haven't already tried this I would as a test only plug source components in to the PP.  Leave the amp out, then if no improvement plug it all into the wall (no conditioner at all).  Also, go back to the dealer and have them plug it into a system and notice the change if any.  Good luck.

I would send it to PS Audio for Eval.You should be enjoying the upgrade

If you think that it is going to sound great out of the box...it's not.  I leave mine on 24/7 and as I recall it took a good 10 days to settle in.  Initially I freaked out because it sounded worse than when connected to the wall socket...but now it's simply incredible.  If after the break in period it still sounds bad...then I would contact the dealer.

PS Audio has a 30-day 100% refund return policy. Send it back if you’re not happy. Easy solution.

Been using many iterations of PS regenerators since late ‘90s, their PP1200 (20yrs+) trouble free (only needing fan changed twice), always brought improvements to whatever plugged in (various—too many to list over those years).

Recently, just for peace of mind sake~thinking too old (but they still work flawlessly btw.)—while looking for new, auditioned some of those mentioned above plus few other popular auto voltage regulator types. Again, ended up with P20 clear winner in my system. 3D, resolute, dynamic all the while sounding v.natural/organic ie.no stripping/washing off colors as many do. And that saying with my main (dedicated) started reasonably ok—with less than 1,5% THD in on average, and very little voltage irregularities if any.

If sure not a faulty P15 you got—I’d try let it settle a bit more whilst try play around with adjustments. Sine/multi, also—tune voltage out—as few volts up/down could alter sound quite markedly ime. Also, power cords into/outward of it play a big role too. And if possible, separate power amp from sources on different dedicated mains using two PP (even smaller ones ie. 2xP10), this will further bring upticks in sound—cleaner, better separation and open up the soundstage even more, imo.
Can’t imagine living without them in my system. Good luck.