blue tops are deep cycle. THe yellow tops are suppose to be a cross between a deep cycle and reg battery. I had one last for ever. They are suppose to have better run down properties.
deep cycle doesnt really matter if ur not discharging the battery often. For audio u want something that can handle quick bursts of high current draw and delivery the power as fast as possible. Its my understanding that the marines are the hybrid and the yellows are deep cycle :shrug: