Hi Folks,
This is just my second post and it seems appropriate to introduce myself, detail what I currently use and what I am hoping to accomplish. I apologize in advance for the length of the post.
Current rig:A-Guitar into a true bypass wah-wah then direct to:
B-Marshall Class 5 through a speaker level direct box into 1/2 of an early 70's 1960B cabinet with 25 watt 75hz greenbacks
C-Direct box out into a Lexicon MX300 effects processor used primarily for delay/echo and rotary speaker effects
D-MX300 output into effects loop return of a Marshall MGHDFX100 amp into the other 1/2 of the same 1960B cabinet. Using the effects return bypasses the whole preamp section, but provides an added benefit of being BEFORE the digital reverb and effects (chorus, flanger, etc.) of the amp. These "on board"effects of the amp are already well tailored for guitar use and work wonderfully without much tweaking.
This setup works very well as the input of the MX300, as well as the input of the MG amp, gets the full sound of the Class 5, helping to make the delays and other effects sound very natural, especially long echoes, up to 5 seconds. This ends up working as well as having a sound engineer add these effects through the FOH console, except that it puts the control of their use in my hands. The Class 5 sounds pretty fantastic, except for limited variety of tone, a little flabby/tubby in the low end and once the second amp is added, it can be a little louder than some gin mill owners are willing to accept.

It seems a little pointless to try to add any kind of power scaling, PPIMV or VRM to this amp, given it's already limited capabilities.
Hopes/GoalsA-Get a little more tonal variety/choices
B-Get a little more low end clarity, not cleaner but more clear and defined
C-Good control of apparent volume without loss of tone, dynamic response and harmonic guitar feedback.
I tend to run my "main sound" amp generally floored and play with a very light touch (no pick) and live just on the edge of full blown feedback/howl and just oozing all that harmonic Marshall goodness! I like to refer to my tone/sound as "Screachin' & Squawkin'".

It seems that an 18 watter with VRM might be just what I need! Possibly even less wattage, but with the same preamp section might be appropriate?
Any and all help, advice and comments will be warmly received.
TIA,
Gene