Upgrade suggestions from BAT VK-300xSE


I'm looking for advice on an upgrade from my BAT VK-300xSE, without breaking the bank. I'm considering Audio Research LS25MKII & 300.2 or VT100MKIII (used). Or BAT separates, but I've been told; that I'd have to go way up the line to better their Integrated by a significant margin.
My Speakers are Wilson Audio Sophia.
My Source is Krell SACD StandardV.2
sunset_ranch
I'm a 300X-SE user who formerly owned an ARC VT100 Mk-I &
Mk-III.
I'm my circumstances (smaller room, lower volume listening) I much prefer the BAT to the ARC.
The tubes generally sound "polite" and homogenized -lacking in color and texture.
I swapped out the ARC for some borrowed BEL 1001 Mk-V monos ($8000 pr.) and was stunned by the improvement!
I guess I'm just a solid-state guy at heart.
I'm leaning towards the BAT VK-31SE (good deals on out-going model) & BAT VK-250, which I will demo. this week, though it won't be cheap at $12K-retail (2X the cost of my VK-300xSE). I'd rather not mix-and-match pre-amps & amps. Manufacturers of this caliber go through a painstaking process when voicing (tuning) these components for optimal mating, and I doubt that I could better. The ARC LS25MKII & ARC VT100MKIII are my second choice, at around $5.5K-used, though I’m hesitant to take on the bulk, heat & maintenance of a very large tube amplifier.
The last time I checked, a VT-100 factory retube (power tubes only) from a dealer costs $850.
This is every two years if amp used daily (1-2 hours) and weekends (4-6 hours).
You can use non-factory tubes, which go for around $400,
and bias yourself.
This is partly why I switched to SS.
i ran a 300xse with my sophias...then stepped up to 31SE/75SE. whole different league at that point. 51SE was an even greater improvement.

good luck!