I recently heard a pair of Sonus Faber Auditor M speakers. Boy did they sound great, but then for $5,500.00 I guess that they should. Are the Auditor M's a better sounding speaker then the Concertos? It's easy to go to a show room and listen to the Auditor M, but the Concerto's are older and I know no one who has these to listen to them. I never knew a speaker that sized could sound that good. Are they better then the Concerto's and is the cost difference really worth going for the Auditor's compared to what you can buy a used Concerto's for?