I need a little help tuning my headunit: Alpine CDE9881

Alpine Type S speakers in my doors
Kicker KS40 in my sail panels.
Components are running on a: PPI Powelclass 650PC

Nitro BMW484 amp
driving a 10" Boston Acoustic G3 sub

I had everything tuned and it sounded good originally but I got curious with playing with the different options and experimenting with sounds on the headunit and ended up getting some better sound when messing with some settings. Others however made it sound worse and I wanna know what would be a preferred option to get the best quality out of these settings or is it all just a matter of opinion?

These are the options that I don't really understand so help would be appreciated.

My headunit has a button called A SEL.
This allows you to tune Bass>Treble>Hpf

Now my issue is when playing with some of these settings I was mostly playing with bass/treble options. My HPF was set to off originally because I believe its configured correctly already thru the amps which were professionally installed, so I wouldn't need to have it on. When I attempt to adjust HPF to a different level it doesn't sound as good so I guess I will leave that off for now unless you think otherwise.

My main question is this Alpine headunit has different bass frequencies when you hit BAND. 80Hz 100Hz 200Hz 60Hz 80Hz where should I have that set for the best sound for my boston acoustic g3?

The other option it gives me is for Bass Bandwith 1(narrow)2>3>4>(wide)
where should I look to have that set or is that preference also? My guess the lower the more punchy sounding my sub would be I am assuming?

Treble Center Frequency options I have currently set on 12.5kHz and it sounds good but where should they be?
10.0kHz 12.5kHz 15.0kHz 17.5kHz 10.0kHz?

and last but not least

Bass Level -7 thru +7 currently at 0 (I usually use the rotary button to adjust bass by pressing then turning the rotary **** is that a different bass setting then by pressing the A SEL bass options? )
Treble level -7 thru +7 currently have it on +1 and it sounds pretty good.

Anyone have a smiliar setup and could share some light on my situation or is this all a matter of taste? My main concerns are the frequency options for my components and sub? Can someone point me in the right direction for what I have. I achieved a pretty good sound that I like for now but I want to make sure I am not doing any damage to any of my equipment with my current settings and if there's a way to get improved sound quality from just adjusting some of these settings around?

My gains and settings on the amp were professionally set so I am not worried about hurting the amps just mainly concerned about the speakers and sub being affected by these changes. It just gives me so many different sounds and options and I would just like a little more info from a pro. Thanks.

 

On any HU I set the low pass to 120-125hz and high pass to 125hz its really tuning to your ear and to what your.speakers.can handle before they distort.

As far as EQ settings I don't use any, bass boost I don't use at all I prefer straight gain and minor.boost from the amp.