I've had a few different parametric eq devices in my bass rig and have found never found them useful. Theoretically, they offer the best way of tailoring your sound to fix problems with your equipment or with the room, but in practice I've found that they offer too many options. As long as the frequencies are correctly specified, a broader based five-band tone control works for me. Even then, I find I only ever need to use the low bass and lower-mid bass controls in live situations.