You're over complicating things a bit there with your setup Dougie.
Most of us here like to keep things simple....with good reason
Between them it sounds like your Presonus and PC are doing some unwanted processing (have a look in the Windows sound settings for what it might be doing) - and that's before you start playing about with Denon trickery
Do yourself a favour and keep things simple boy.
(Go back and look at some suggestions on the other thread).