If you want to maintain tonal balance at SPL far from the original sound level there is really no way to do this other than electronic equalization. Old time preamps addressed this problem with a "Loudness" control, which is just a volume control the effect of which is variable with frequency. Today you probably need an equalizer.
I am very happly with the Behringer DEQ2496 which costs only about $300, and includes a RTA so you can see what you are doing (provided you also buy the mic for $70). With this unit you could store several equalization curves, corresponding, in your case, to different SPL, and perhaps different types of music. It's not a big investment ...well worth a try.
I am very happly with the Behringer DEQ2496 which costs only about $300, and includes a RTA so you can see what you are doing (provided you also buy the mic for $70). With this unit you could store several equalization curves, corresponding, in your case, to different SPL, and perhaps different types of music. It's not a big investment ...well worth a try.