No experience with Bel Canto but I own the Cayin A-50T driving a pair of Nola Boxer S speakers and it is an incredibly satisfying combination, probably the best sound I've had in 50 years of swapping gear, both tubes and SS, some of it considerably more expensive than this combination. The Cayin is a remarkable bargain.
The stock tubes with the Cayin are pretty good, new production Russian Mullards in mine, but I think it's worth the money to switch to Gold Lion KT77s.