On Saturday we used a house pa with alto tops and a single H+H sub.
Our vocalist used his desk and started by equalising with white noise and a reference amp. Then he let the system ring out any feedback automatically.
I asked him not to low pass my bass, he showed me the default curve which was a hpf about 40hz, a slight dip at 4-500 to make space for guitars, then flat.
Positive comments from the audience, which inclded a few musos. ! few people here have commented that my bass sounded 'really deep' on what are just phone recordings.