Hello iardon,

The sub output in 5 stereo will be louder than that of standard stereo as you're summing sub frequencies below the respective crossover points and redirecting that to the sub. That would be 5 channels worth of sub signal vs. just two.

I would also suspect your sub was in a music sense mode which could cause a delay in its activation relative to the amp which is likely being powered up through a trigger connection. Give us a call and we'll be happy to help you work through all of this.

Best,

Scott