preamp inverts polarity

That is utter nonsense and it’s likely you know that...man...

Wolfie, your response is somewhat indicative of a two-year trade school education.

I listen to "redbook" CDs frequently and although my DAC has a polarity switch, I rarely use it except to check if "maybe" something is out of phase, but generally nothing is and they sound great. Thanks Kaitty, a two year trade school education would have been great!

"...except to check if "maybe" something is out of phase,.."

I don't think your ears will be able to tell the difference unless you have a "phase correct" reference you can compare with. I listen to a lot of the same music albums on both LPs and CDs and I occasional run into a CD/LP where I can easily\y tell the difference but it is more like the channels are reversed because both media sound good and nothing seems to be missing.

Got some bad news, Wolfie. You is officially deaf. Is it too late to request a full refund from your trade school?