I owned a pair of Signatures 805's and powered them with a pair of Manley Snappers. In Ultralinear mode (about 100W) they sounded great. If I ran them in Triode mode (about 33W) per side they ran out of steam quickly. Dynamics, bass and sound-staging did a nose dive. The Luxman is a great amp and the B&W's are great speakers but I think you would be better off getting a more efficient speaker or a more powerful amp
Good luck
Good luck