I have no clue what petrucci used on any album and if I did, and could afford all the equipment, I still wouldnt be able to sound like him anyways.
Anyways to the original poster purplecastle,,, I own a ROV series 2 combo,,I will start by saying that I believe trying to achieve the best lead sound ever, you probably could do better with something other than the ROV. But on the other hand I think you could do worse. Ive been slowly finding my way to a better lead tone also with the ROV.
You had mentioned the bb preamp,,,I own and use that with the ROV and I couldnt suggest a better OD/boost for you. I normally use it to boost and add gain/saturation and to tighten my leads. It also works very well simply using it with the clean channel alone. Beautiful rich tube sounds come from this pedal with quite a lot of available sustain. Let me say that adding this did not turn my ROV into a perfect lead amp by any means but it did help.
I also run a boss ge-7 in the loop which seems to help a bit,,note,,I had the MXR 6 band eq before this and it created a loud thumping sound when I raised any of the bass knobs at all.Remember the 6 band does not have a volume level so your 10 band may work fine.
I dont know for sure or not if the head version you own has a built in reverb like the combo but I assume it does ,due to its name,,
believe it or not one of the best things I did to achieve a more beautiful lead tone from the ROV was to add a reverb pedal and use it in the loop.
I found the ROV's built in reverb to be a little weak,,adding the pedal made it sound so much better,,now I have REVERB.
I noticed you had mentioned the dynacomp compressor,,I have never purchased a compressor before but I have thought about doing so,,I wonder what you think it might help with your sound assuming you would use it with high gain lead work,,,I ask you this because I just dont know,
all the compressor samples I find on the net use them with clean sounds only so I have been reluctant in pursuing one,,any help???