The new AN Kit 1 mono blocks heard at LSAF had more bass weight than I remembered from the stereo Kit 1. Upgraded power supply. About $2500 IIRC.If you can work from a schematic, or have your very own Steve Brown, the Simple 45 has great bass definition and texture although more lightweight than solid state or valve push-pull. About $1200 the way we (okay, I mostly just watched) built it.
I'm still so impressed with it in comparison to several much more expensive commercial amps, I just ordered upgrades for the plate chokes and output transformers from Magnequest: BCP-15 chokes gapped especially for the 45 tubes and EXO-45 ALL NICKEL(Yowza) OPTs.