Music production? Then you definitely do want super-extra-quiet.
The primary way to reduce noise is to move the air slowly. One large outlet with 4x120mm fans turning slowly will work well. Pushing the same flow rate through the area of one fan will need higher airspeed and more noise. The inlet should be about the same area as the outlet. Then maybe one baffle over the fans so that you can't see them from the outside = no straight lines for noise to escape. But be careful not to reduce the area available for airflow.
If there's just servers in this box and no other heat-producing devices, then I would plug the fans into the servers so that their motherboards can control the fan speeds. This is a problem that's already been solved for regular computer cases.