I currently drive my Extremas with Convergent Audio Technology JL-1 Monoblock tube amps using KT-90's as output tubes.....in one sentence they are the sound i have been searching for in my 30 years of being an audiophile!...i originally mated the Extrema with Classe CA-301 and they sounded very thin and lifeless with linited dynamics....do the research and you will be happy you did!...you can e-mail me with questions.
Jeff
Jeff