I have an old school Planet Audio 1250 without the bass knob. Does is effect the sound and output of the amp like the bass knob did for the old Rockford Fosgate amps?
I like to refer to it as a "remote woofer cooker".
Once set, your gain needs little/no adjustment.
If it is a +db type?
No, it generally adds distortion to a system that is already "set".
IMO Most ppl use it because their box is "peaky" and they try to make up for shortcomings from it. IE....to boost frequency's your box really cant do well....many of these same ppl dont have the power they think they do (impedence rise, lack of v, overrated amps) and it spells disaster.