Enjoying this thread. I have never considered Decware although I have read and heard good things about them.
I have 2 set-ups that I run on my Belles which I think are end game. Both are sourced by an Oppo 203 and use an SVS 2x12 1000 wpc sub. The first uses a PrimaLuna Dialogue Preamp and a First Watt SIT-3 amp (18 wpc, Class A, single ended). The PL + the SIT-3 combo approaches the midrange smoothness of an all tube system. Credit to the quality focus of the PL team and Nelsen Pass' amp design.
My second setup uses a CAD-300 SEI integrated amp from Cary Audio (this was designed when Dennis Had still owned Cary). I upgraded the power tubes to Western Electric 300B's last year from WE's relatively new factory in Georgia. After 6 mos of tube burn-in this 15wpc SET amp really brings the best out of the Belles. Super smooth mids and highly resolving top end. The imaging is so impressive.
This is Zen for me!