29Hz-20KHz +- 1.5db!!! These are very close to a full range speaker. 86db efficient 4 ohms, they are giving the M504 a work out! Recommended minimum amp power is 100 watts per channel. I don't think they'll work with my 5 wpc tubie.

Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.