90s EHX Deluxe Electric Mistress

[azrael]

I have a 90s reissue of the DEM and I am looking to improve it.
Is there anyway I can reduce noise?
Two things I have tried include:
-replacing the 4558 with a TL072, which helped a bit.
-putting electrical tape on the bottom of the transformer, to isolate it from the chassis. This reduced noise a bit.

My next concerns:
- I get feedback when using the filter matrix mdr with OD, is this normal, ad do I just have to roll back the color knob some?
- how can I remove the AC cord and use it with either batteries or preferably, a power supply?
- any other mods I can do? I'm going to try tweaking some of those trimpots soon..