My scale kinda goes like this. you get what you pay for and if its
Less than 10 cents a watt = used OK , new watch out it will blow eventually unless you keep it at rated ohms and over 12.5v input
10-15 cents a watt - new - ok (audiopipe), used - reliable
15-20 cents a watt - (AQ)(MBQuart) - new - reliable , used- should not be able to blow with daily use
20 cents a watt+ (sundown)= should be special like 16v/.25 stable, never blow as long as you keep 12v to it. or your getting ***** (JL, memphis)