Tekunda, your brother should be asking which speakers would not be a good match for the Tenor amps; they are a lot more flexible than what most people think, especially for an output tranformerless design. I have heard of very good results with Wilson MAXX and Watt/puppy, the Kharma line, Talon Khorus, and at the upcoming Hilton show they will be paired with the (new) 7' Pipedreams. This will be the amp I will invest in once my upgrade from Raven to Khorus-X is accomplished.
To make a long story short, give Jonathan Tinn a call at (503) 221-0464 or (425) 454-2279 - he is a Tenor dealer in the Northwest and has a great deal of experience with them. You may also want to touch bases with Francois Lemay, one of the Tenor principals (email@example.com). Best of all, come to my hometown of NYC and meet both gentlemen!
Good luck. If you have plans to come, let me know.