Music is divided into 7 frequency spectrums:

1. Sub-Bass:                 16-60Hz
2. Bass:                         60-250Hz
3. Lower Midrange:      250-500Hz
4. Midrange:                 500Hz-2kHz
5. Higher Midrange:     2-4kHz
6. Presence:                 4-6kHz
7. Brilliance:                  6-20kHz

Generally speaking, an increase of 10dB roughly corresponds to the perceived doubling of intensity

Max output voltage of a 3.5mm jack doesn't seem to have a standard limit, will have to figure it out experimentally