Luxman 550 A II 20 Watt what that means?

Yeah.Luxman to me is the new Accuphase and I drool when I see them (got in touch with ex reviewer for Soundstage who took plunge on one with some esoteric two way floor standers).But your speaker are 89.5 sens at a 4 Ohm load.I don't think it's enough top push them up the hill.Did deeper and get 590.You speaker company recommends 50-400 wpc.The 550 is 40 in 4ohm and the 590 is 60wpc into 4 ohm.If your room is large enough for those speakers and you want to get any volume the 550 probably is little to little.
Chazz

Unless you have a big room, the Helicon 800 will not work well. I drive the 400's in a decent size room `18 by 15 with the Luxman and they sound great together. The 550 MK II sounds as loud as the 9100.