could be ur hu what kinda do u have matbe the preouts suck but i think i saw a premeir in ur car not sure.. uhm that or the gain is bad u dont know it do u have any frequiencies settings on ur hu
i think i may know what you are talking about.because when i had my power acoustik amp, my subs made a sort of popping sound when i turned my HU on. it was because the amp was cheap and didnt have some of the filters that good amps do.this seems like a similar problem. but now that i have a good kicker amp ive never heard anything like what i described above.
na, nevermind, you got a good amp ...but i still think i know what sound youre talking about. it wasnt musical at all, just like when power first reached the amp, it sent a small signal to the subs, atleast thats how it was for me