If you are thinking open baffle with subs like the Prometheus MKII from Bastanis, or PHY 30, these speakers are very efficient (100 db), IMO the 300B is an excellent choice, or other SET amps(2A3,45,PX25). I've heard the Bastanis Prometheus MKIIs powered by 300Bs(DIYHIFI Ladyday) and PX25s(ART Audio) and with powered subs and 100db efficiency, these will rock.
