I'm suprised your Denon would not have enough umpfff to drive m3's to plenty of volume without distress. Heck my 80's did fine with my Denon 2805 in almost a 8,000 cu ft room.

Anyway, I would also recommend Odyssey like Brandon. I have the Odyssey Khartago Extremes (special built by Klaus) which are basically the same as Stratus Mono's.

Good Luck, Randy

ps: As Wid mentioned, I would almost look at larger speakers as your your external amp may just be unused amperage.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85