In a good system everything sounds perfect at zero unless you are playing a low-quality recording. People find it hard to believe though. Since so many of us upgraded from subpar systems where we're used to playing everything with all the settings cranked to the max to squeeze all the bass and highs that we can out of it, it's hard to even recognize what natural sounding music is after awhile.
It comes from people getting conflicted and not building a system with a clear sense of purpose. They design what turns into an SQL system when they really wanted SPL but didn't want to pay for and install big or multible subs, and wonder why it doesn't pound. Or else they do huge subs and sub amps, stick cheap coaxes in the doors powered by weak four channels, and wonder why all it does is POUND. The end result is something overwhelms something else so certain frequencies are artificially boosted to make up for it, leading to distorted tones and eventual damage to the equipment.
For awhile every time I went to my audio shop I got chastized for having my treble on 6 and my bass on 4 on 5. I've learned my lesson now and everything stays flat. Occasionally my bass might go to 1 if I'm listening to bass-heavy music on the radio where it doesn't hit as hard as if it were played from a CD or IPOD. Sometimes treble might go to 2 or 3 if if it's an older low quality, low volume recording of an old-time Blues song where the instrumentals aren't that clear. The higher and more often you need to crank treble and bass, the more likely there is a deficiency in your tuning or your equipment. It takes awhile getting used to but the longer I keep my HU tuned like this, the better everything sounds. Most of the time I find nothing lacking in my music with the settings at zero or close to it.
It sounds like maybe your substage is overwhelming your front stage and you are compensating with the head unit adjustments when the real goal should be to figure out what changes to make to put everything in balance.