AT4000 SIGNATURE SERIES. Available with 2 to 7 channels, the AT4000 series amplifiers share the design philosophy and circuit sophistication of ATI's award-winning AT6000 series amplifiers at a reduced power output of 200W RMS per channel at 8 ohms and 300W RMS into 4 ohms. Plus, their "Signature Series" designation with a facsimile of Kessler's signature on the main panel attests to the special nature of these amps..PZA MORE SPECS