You have 3 options, 2 of which are tubes... If you're unsure of which direction you wanna go, have you thought about a used Lyr3 (could be had for cheaper) or lastest Lyr+?
The Lyr+ would give you the best of both worlds. Solid state music... then when you fancy a bit of tube flavour, just pop in a 6SN7 or equivalent of.
For Lyr 3, I used to have Schiit Lisst tubes which are solid state tubes basically. Just pop a Lisst in th hybrid Lyr 3 for solid state, or use the forementioned 6SN7's.
Schiit Lisst
I've been using my MG P's with NJC reference DAC and amp. Loving the reference detail (but not analytical). However, just today I took delivery of a Tor Audio Nick amp, paired with the NJC DAC for a bit of tube flavour. Well, I say a bit... there's plenty of tube warmth - full, rich sound. It's early days yet, and I haven't read all the thread, but imo the MG's seem to play well with both tube flavour and SS. I would deffo recommend you consider the Lyr if you're a bit torn between tube and SS.
Which DAC(s) you using? Not that I'm that experienced by a long shot to convey an opinion based on that - I've only tried/had about 10 or so. Was just curious.
Unfortunately I sold my Bifrost and Lyr 3 before the MG's came into my posession. So I'm only guessing that that amp (Lyr) would be a good choice for you.
BTW if you do decide on Little Dot III, see screen snip in case you aren't aware. Also including my Tor amp, pretty chuffed with it!!
I'm considering the Clear Mg Pro but I HATE the red pads. I previously owned the standard Clear Mg with a silver Norne cable. That provided a leaner more detailed presentation that worked for me. I can't find the Elex pads anywhere, so the Utopia pads might be my only option.
Said that, the Clear are more punchy and slammy than HD600 and HD800, quite a bit more actually, makes you feel you went next level. So I guess the Clear would be a worth upgrade path in that sense.