I just tried a pre/power combo from Gryphon thanks to a loan from the dealer - the BelCanto and S100 were here for a week or so, my findings:
PROS
i) better bass control and energy
ii) nice headroom and around-the-speaker air reproduction
iii) great look and build quality as all Gryphon gear
CONS
i) not as magical and musical as my Acoustic Plan Sitar hybrids
ii) more fatigue after a couple of hours compared to my reference
iii) asking price to move does not justify the effort
I decided to keep my Sitar until other options become available.
Thanks to all the replies so far, de Bearning was not in my list and will definitely explore it.