Right now mine is playing on a pair of Altec 421 woofers and 811 horns/806 drivers. It sounds pretty darn good actually. Drives them with very little heat on the heatsinks so I geuss they are not being overdriven. I have Brian GT's extra special kit that I will put together soon and see if there is a difference. I get nice full and deep bass outa them on the Altecs. J.R.