Each and every amplifier we manufacture is tested twice. Once at the semi-finished PCB stage of production, and then another test is done at the final assembly. We also run age tests on them. After this is all done, we hire a 3rd party independent company unaffiliated with our factory or with us to go to the factory and inspect 20% of all the production items. We test the power, the controls, and over 20 other tests. We guarantee these amps will satisfy you. We are so confident in your satisfaction of this amplifier that we will offer you a 90 day money back guarantee. If this amp does not perform as well as you expected we will send you a pre-paid shipping label and give you all of your money back. This means if for any reason you want to return the amplifier back for a full refund within 90 days, you can! (Amp must be complete along with the box).