If Class D is too clean there are a few simple tweaks you might try. Obvious but slow is to just let the dust build up. If the sound is a bit dry and gritty and you would like a smoother softer focus try the Playboy Tweak, a thin coat of vaseline. Very popular all through the 80's. Keep in mind a clean amp is just the beginning. Don't forget to clay, polish and wax.
