Hello thought I had some knowledge on the MA Audio Old school Quality. Have had hundreds of MA Audio pieces am 59 and have been in home and car audio for 44 years have had two MA Audio amplifier of this model over the years.i am pretty sure they didn't really use any maximum wattage ratings. Any of the companies back then so. MA Audio M1889i was pretty much dead on 400wrmsx1@4 ohms/800W x 1@2 ohms was An RMS rating. I believe the company relinquished any responsibility if the amp put out a Maximum burst of 1200 watts and your pair of 1200w subs blew. I would conservatively say 800 Good clear watts at 2 ohm up to 14.4VDC . To get big power from any amp you have to feed it an adequate power supply. I recall MA Audio had a lot of high current amps that required a pretty good steady flow of current. Working the amp is definitely worth around $100. The stuff you buy for $100 now days weigh less than 1/4 of the weight. Lots are more efficient and smaller footprint. But the good Quality definitely comes with the BMW or Audi price tag. Hope I have been of help. MA Audio always made solid pieces as far as I am concerned. Happy Holidays.