Oops, I did it again and wrote another novel.... sorry for the long post :roll:
The flux drive is a mark in the box where as the throttle box is a rectifier in a box. I have both flux drive and grid slammer and they do wonders on the Mark V, and JP-2C. Yes I said the JP-2C! Trick with the flux drive is to use a lower gain setting on the pedal and the amps will just flourish with all the juicy zing you cannot get with a simple tube swap. Unfortunately the flux drive does nothing for the Roadster... On the RA100 or TC-50, input is a bit on the sensitive side so it is difficult to run any OD or tube screamer on the front end. I would have to re-visit the TC-50 with the flux drive and or grid slammer as I do not believe that has been tried since I got the TC-50. I did attempt with the RA100 and was not overjoyed with it. Those pedals are a hit with a Mark amp.
Considering the original post, I would assume that it is desired to have all three channels independent from each other. Sure the Mark III is an awesome amp but will take a considerable amount of time to dial in a clean channel or bluesy channel since all of the controls are shared. I had one and it was just dial in what you like and leave it there. Changing from a desired Rhythm tone and then to lead did not always amount to an easy task as I may want more bass on the rhythm and higher gain on the lead. I did love the Mark III but did not like the decoder ring style of dialing in the settings. (needed manual or templates to mark the settings to reference, a cell phone would have been a better option but I did not have one at that time). The same issue relates to the Mark IV such that the two rhythm channels shared common mid and bass but had separate treble. Still a better alternative to the Mark III but not ideal. The Mark V solved all of those issues but also had one other that was not easy to overcome until recently (hence the saturation mod thread). Also the Mark V is the reason I tossed all of my rack gear as the units were not compatible with line level signals when using the MKV FXLOOP. There are some products out there that will do level shifting (for example: Ebtech LLS-2), had I seen it I would have been able to keep my old gear and some pedals that would not work at line level. Oh well, I do like the Strymon stuff anyway so it was a good move. I can even use them with the Mixer so there is another benefit there. They also work well with instrument level too.
I will admit after doing the saturation mod on the Mark V, I love it just as much as the JP-2C. And the plus to that story is the V has more vices to choose from vs the JP. What is not apparent in the JP-2C is I can dial in any tone I can get out of the Mark V with the exception of the Tweed V:CH1 or Edge V:CH2 (probably the most useless voice on the V as there is nothing British about it with the 6L6 power tubes in use, also brittle as heck). Kudos on CH2 would be for the Crunch and Mark I. All of CH3 is usable with the tube swap mod. The JP-2C does not need any fix to make it sound awesome, it just does.
TC-50 is a well loaded amp. CH1 has to be my favorite for clean to gritty blues and even classic rock. CH2 is your crunch channel but can be used as lead as well and CH3 can be anything from medium clean with clip to just down and dirty chug metal. It is quite versatile as I generally play more classic rock (led Zep, ACDC)
Now we can limit down to three models: Mark V 90W, JP-2C, and TC-50. All of which have independent control of each channel (presence, treble, mid, bass, gain, volume). Only two of them can be run in silent mode (JP-2C and TC-50 using the cab clone). Only two have midi control (JP-2C and TC-50) but is not a selecting criteria ). However, there are only two on the list that can be loud as well as sound great at bedroom level: Mark V and TC-50. Sure the JP-2C can be used at reduced volume (to compensate for the increased bass us the shred switch to regain some treble and cut the bass a bit). The JP-2C is primarily a concert amp and best suited for gig level playing. A true beast but can be tamed for lower volume, but not bedroom level by any means unless you get a reactive attenuator or power load box. At least you can use the JP-2C in silent mode with headphones. Mark V currently does not have that feature (cab clone).
The two amps that have Master control on all three channels:
Mark V (when using the FX loop active) and the TC-50. Both also have a solo boost control that is foot switchable. Only the TC-50 has the midi.
The two amps that use independent Master controls on all three channels:
Mark V (when the FX loop is in hard bypass) and the JP-2C (does not have a global master control or solo boost).
Two amps that have cab clone for silent playing (head phones)
JP-2C and TC-50
Two amps that can use other power tubes than what it ships with: (6L6, EL34, or other)
Mark V (6L6/EL34), TC-50 (EL-34, 6V6, 6L6).
The TC-50 fits many categories. It is a bit different than a Mark series amp in its tonal pallet but fits the classic rock and blues so well. Does not require 5BEQ as the full tone of the amp is well tuned to sound great as is. Clean channel is very nice for many styles of playing and is the most versatile of the three. Not quite a Marshall, Vox or Orange but similar, not exactly a Mark or Rectifier but similar. What ever it is does fit most styles. I could not decide between the JP-2C, Mark V, or the TC-50. All are great choices. It depends on what exactly you are after and will you find the tone you are seeking?
If you are after legendary Mark series Mesa tone, the JP-2C is the ideal, Mark V with saturation mod is the other. But sometimes the Mark tone does not fit the song or style.
The hard thing to do is to find a place that has the amps in question and try them out, still the recommended choice if the option is feasible. This may be very difficult for many of us to do so. I had to drive 560 miles out of my way to get a test drive on the TC-50 (was on Vacation visiting family so was worth the drive). Also compared it to a new Mark V. Had opportunity to compare the Mark V:25 and V:35 and JP-2C as all of them were there in the store in NJ available. I was on Vacation in PA so the 1.5hr trip was no big deal vs the 10 hr it took me to get there from NC) I think it is more difficult to decide based on recorded videos or clips since the real feel of the amp in person will reveal the actual tone you hear when you play though the amp. It may be a bit different than what you hear in recordings. One thing I can say about the Mark V even with the ice pick tone, it records well as some of the content gets filtered out and can be altered after the recording. With the saturation mod it sound awesome in person. TC-50 sounds better in real life than the recordings as does the JP-2C. In both cases after unboxing the amps I was not immediately impressed. TC-50 was a bit harsh and bright (burn in the tubes and mids just blossom oh yeah). JP-2C seemed a bit lame but at bedroom level it will. Where is the gain... it is there and plenty of it too. Read the manual usually helps a great deal and forget about what you remember from other amps on how to dial in the settings. Sometimes it is great if you can demo an amp since it may be past the burn in phase of the tubes (EL34) or power supply has settled to its nominal levels.
As for a Cab choice, the Mesa Recto Vertical 212 has got to be one of the best sounding cabinets I own. Sound is huge, tight bottom, overall well balanced tone and despite its weight (70lbs) it is easy to carry due to the side scooped handles. I also have two Mesa Recto OS 412, one Recto horizontal 212, and a modified Egnator traditional sized 412 that I changed speakers it was cheep and the materials of construction indicate it but it sound good enough to use. In all of my cabinet options, Vert 212 is my favorite. TC-50 and the Mark V head will fit just well (too bad my Mark V is a combo
). JP-2C having the smallest foot print will have no issue sitting on top.