I've got an Ampeg Jet II 12R that is very warm and clean at low volumes. It does saturate fairly quickly above about 6 or so, especially with the reissue Mullard EL84's in it, but with the Reissue Gold Lions and some 7025's in the pre amp it is very warm and clean indeed. Some literature suggests that it is a Class A amp, some sources say it is Class AB, so i can't tell you for certain. It does not get flubby in the bass at all, unless you dime the bass control at full volume, and that is with the stock speaker, and i have had the amp since 1994.

another solution involves the BM50, but is a little unorthodox and requires a c-lator, which i can't recall if you use or not. I have been fiddling around with mine quite a bit lately, trying to get Freddie Kings nice warm, yet bright non flubby sound that was a clean, yet overdriven sound, you know the type. He tended to use big clean amps pushed hard, like dual showmans, twin reverbs, concert amps, etc. The big key, though was that he set all the tone controls except the treble to ZERO. I figured the BM is close to a BF fender, so i gave it a shot. First, i pulled the larger 6L6's out and put the JAN Phillips 6L6WGB's back in, and biased them at 42 mA (the lowest i can get them with my current bias circuit). Those little tubes have a much tighter bass response and better upper mid and treble response as well. then i ran all the tone controls to zero, including the presence, and turned the treble up to 10. I turned all the bright switches off, midboost off, and deep off set the preamp volume to 7 (about 1 or 2 o clpck), the master to about 10, set the drive control on the c-lator to about 1 clock, input wide open, about 5 clock, and used the out to control the overall volume per normal. Bear in mind i have Weber 1265 Alnico speakers, which are not as dark as standrard g12-65's, they are a bit more warm and bright, rather than dark and wooly. I gotta tell ya, it sounds gorgeous! Nice and warm and clean, a little dirty if you dig into hard, and gets a nice warm overdrive saturation sound if you use a nice clean boost pedal, or in my case engage the mega PAB. Very smooth singing overdrive sound, and a nice warm overdriven power chord type sound, not crunchy at all. If you don't have a clean boost or dislike the PAB you can crank the drive control up on the c-lator as well, and it can yield the same results, very nice indeed. Also, unless you engage the deep switch, it is NOT flubby at all, and you can control the volume quite effectively with the c-lator, and since the master is up quite high on the amp itself, it is very lively. Mind you this is all on the CLEAN channel, not the OD. The OD side is even more fun! give it a try!

Awesome that you found a solution that works! As to the Jet, the clean headroom is all tube related. The trick is to find a set that saturates at a higher volume. As Tone Control originally stated, he wants a good low volume clean solution with no low end flubbiness. The BM set up I mentioned above works very well in that regard, as does the Ampeg, at low volumes. I actually had a battery powered pignose back in the day that was very clean at low volumes and wasn't flabby in the low end. Not tube powered, but very simple

i was kinda thinkin the same thing, i just don't know how Tone Control feels about SS amps

agreed. the last SS amp i had was a 150w head, i wanna say it was a brand called yorkville or something. low volume clean was its forte for sure, even though it was a high wattage head. Those lil hybrids from fender like the Champ XD and the like aren't bad either.

this sounds sensible, for recording through my Isobox, I often have to use a multi-band compressor with a mid-scoop to liven up the mic'd speaker
What's a high-enough quality EQ for my lovely amps then? (My favourite OD pedal is my new Zen drive 2 btw)

It's a fair point, you can make a really nice SS amp, and that would be nice with a hollowbody. I had a lovely sounding Hughes and kettner one once, but my Twin did the same trick, so I lent it to a friend who sold it, I only sold him stuff after that! However, with way too many nice valve amps in this room, I'd feel a bit strange leaving them off to play a SS amp. I  want to be approaching the sound and feel I get from the valve amps, and I do live in a brick-built detached house, so it doesn't need to be bedroom-level, just loud hi-fi level. I've tried quite a few low-power SE valve amps (and a low-power PP amp), and they all lack something, I am guessing that it's down to the 50 years of natural selection the bigger amps have benefited from - better designs will arrive one day. The Carr mercury is good, but can flub. My Wienbrock 1w push-pull is good, but a bit too quiet, you can't get much bass out of it of course, and the preamp valve used for push/pull is a very different sound to a 6L6. The 5w Marshall and BH5 are OK, but not great, but that's an growly EL84 sound. I had a BH5 modded to run a 6L6 in parallel. Again, it's good, but not as satisfying as playing a BM50 or DC30
The watkins westminster 10w was nice, would that be possible to replicate? I need to look around..

MXR one looks promising. I had Boss pedals that killed my tone, so I'm wary.

well the same principle applies as with Ceriatone - you can get replica pedals as kits too. Some are very good. I now try to avoid buying a replica if the designer is still making the same quality item at a normal price, but for pedals that are $800 used, I feel OK about getting a kit, same with all the classic valve amp replicas too - I prefer Ceriatone or Victoria to Fender & Marshall reissues