I really love the combination of the G12H-75 with the V30 in the RA100 Combo as this is the perfect blend to my ears. I had to make a temporary extension cable so I could experiment with the other amps. The Mark V actually became alive and sounded extremely dynamic and not sterile. The Mark V does sound better though the Recto 412 but still on the bright side of the spectrum. Though the RA100 combo cabinet it was definitely a considerable improvement so much that I would convert the V back to a head and get a vertical 2x12 and stuff that with a G12H-75 and a V30. I am so tempted to buy the compact 2x12 and swap just one speaker. This is what I may end up doing anyway since that would match the RA100 Combo size and color scheme.
I did try it with the Roadster just for kicks, a little different. I actually prefer my old Recto cab I refurbished as the 15 year old V30 had a darker sound and were not as bright as the new Recto cab. I am so tempted to break the seal of the new cab and install two of the G12H-75's. I am sort of reluctant to do so since the speakers are barely broken in yet, perhaps some other time.
A note on the RA100 Combo, I did not have to change any preamp tubes as the ones that were in were in great shape. However, since I did not have an extra set of the Mesa EL34's (currently in the RA100 Head) I put in the Tung Sol EL34B. My first impression of these tubes in the Head gave the amp more bite and volume when compared to the small bottle Mesa tubes. With the Combo, the Tung Sol EL34B are perfect and do really sound close to the SED (=c=) EL34 in comparison - installed the =c= first but the rattle was driving me nuts. I just did not notice it as much with the new recto cab combined with the RA100 Head. Just thinking about the V30 mix with the G12H-75 is making me drool. Nice and creamy tone, not too choppy or mid level muddy, no flubby sounds, no ice pick either. (I can actually push the treble control up vs all the way down).
For some reason, I wish I never bought the G12H-75 creambacks as this has fueled the need to get more as they compliment the V30 quite well. Definitely worth it. Since I bought 2, now I need another cab to go with it
I am extremely pleased with this speaker.