When you auditioned the Wharfedale's, they were probably in a well damped room. Your fatigue could be coming from an overly "bright" room, and I don't mean lighting. If you have lots of glass, tile, hardwood, etc. you could be experiencing lots of first and second order reflections. Try taming the room with some wall, floor, and/or ceiling treatments. Woochifer seems to be pretty knowlegeable about this stuff so I'd advise you ask him. How a room interacts with a room is critical. Try it out and see if it helps, otherwise you'd better get acquainted with Audiogon and Ebay because a fatiguing speaker is pretty much a paperweight in my book.

Good Luck