I'll give you an operators point of view on audio.
It all depends on how wide of an audio bandwidth your transmitter/receiver can handle. Most pirates use old or off the shelf ham equipment. You can widen the bandwidth to a point, but they were designed to pass about 300 hz. to 3 khz. For ragchewing that's fine, for high-fidelity music, it blows.
I found what Refmo said to be true. I knew my transmitter had a steep dropoff below 80hz. As I've got a deep voice, I would cut the low bass below 100 hz. and give it a bump at 125 hz., then do a slow rise above 500 hz. to 3 khz. cutting gradually above that to about 6khz. Above that, I rolled it down to nada, as most receivers bandwidths cut off about 8khz., tops. (SDR's are an exception.)
Most of the guys in Europe I've talked to cut the top end at 4.5 khz. As they like that "thump" they kick up the bass above 20-40 hz.
You want your transmitter to deliver the most power to where it can be heard. Conversely, you want the filters on your receiver set to best receive the limited bandwidths most pirate transmitters are stuck with.
Noise is something you have to live with as an operator. You look for the sweet spot when noise is low, propagation is solid, and in a time period with the most listeners. Low atmospheric noise is why SW/MW pirates love the winter.
Good luck.