If you have a reasonable amount of time to do sound checks at your gigs and you are experiencing hum/noise, you usually can pinpoint the source starting with all channels muted and then soloing each channel one at a time. Make sure none of your signal cables or power cables are damaged (especially the ground prongs on AC cords, for safety) and that you are using decent quality DI boxes where applicable. You can also keep an outlet tester with you to make sure the outlet polarity is correct and grounding is intact.
If it's in your bass rig, I always start with the bass itself and make sure it's well shielded with copper foil and good continuity throughout all cavities before I bring it out on a gig. When going DI, also test the ground switch on your amp in both positions and set it where it makes less noise. I've had to lift the ground on my amp's DI on occasion. If you have a pedalboard, try bypassing it and plug straight into the amp to see if that is the cause, too. Pedals can be finicky with power supplies sometimes or perhaps a patch cable is grounding to the metal pedal board (I've had this happen and cause weird pops and shorts, even though the cable was totally fine).
So no, a basic power conditioner isn't really needed if everything else checks out. To be honest, I use a Furman AC-215A under my guitar pedalboard to plug in both my amp head and pedals and in some situations it can help a little with line noise, but truthfully the noiseless pickups and shielding in my guitars is far more effective for noise reduction. I just like that it has over-voltage shutdown as sometimes we have to run off of a generator and it streamlines setup/teardown. It's limited to a 10 amp draw, though, so I don't use one with my bass rigs as they have the potential to draw more power than it is rated for. For that reason, I say it's safer to just get a well-made power strip as they should be good with a normal 15 amp standard outlet maximum load.
If it's in your bass rig, I always start with the bass itself and make sure it's well shielded with copper foil and good continuity throughout all cavities before I bring it out on a gig. When going DI, also test the ground switch on your amp in both positions and set it where it makes less noise. I've had to lift the ground on my amp's DI on occasion. If you have a pedalboard, try bypassing it and plug straight into the amp to see if that is the cause, too. Pedals can be finicky with power supplies sometimes or perhaps a patch cable is grounding to the metal pedal board (I've had this happen and cause weird pops and shorts, even though the cable was totally fine).
So no, a basic power conditioner isn't really needed if everything else checks out. To be honest, I use a Furman AC-215A under my guitar pedalboard to plug in both my amp head and pedals and in some situations it can help a little with line noise, but truthfully the noiseless pickups and shielding in my guitars is far more effective for noise reduction. I just like that it has over-voltage shutdown as sometimes we have to run off of a generator and it streamlines setup/teardown. It's limited to a 10 amp draw, though, so I don't use one with my bass rigs as they have the potential to draw more power than it is rated for. For that reason, I say it's safer to just get a well-made power strip as they should be good with a normal 15 amp standard outlet maximum load.
