Why don't you remove the DBX unit, and see how it sounds. I've recently got the best cartridge/tonearm lashup II've tried with this turntable, and I'm hearing the least surface noise, yet the cleanest LP sound I've ever had. It would never occur to me to use a DBX unit in my situation.
Turntable is a 50+ year old Garrard 401, arm is old as well, a Dynavector 501. Not a great deal of moey involved, just a great deal of DIY.
Hope you get it figured out, good luck,
Dan