I was hesitant to buy this product as well as the NAU 660 that I bought at the same time. I knew MB Quart was a solid speaker company, but was not familiar with their amps. I bought these two amps to drive 10 seperate Polk Audio speakers in my boat (six in the boat, 4 on wakeboard tower), driven by an Alpine head deck. All I can say is WOW! I can run my system at Volume level 31 out of 35 with no detectable distortion and solid quality sound. I have had my boat out probably 20-25 times since the install and have not gone easy on the amps, so far they are still performing perfectly. The only issue I had on the install, was the speaker connection configuration is different between the 460 and 660, so if you happen to get one of each pay extra attention to the wiring diagram. I am one very pleased customer, and already have recommmended these amps to friends (who love the way my system sounds). I might add, I buy many products off of the internet and reviewing these two products are the first time I have taken the time to write reviews, only because of how impressed I have been with the products.