Grado/Rega Hum

Unfortunately, I have two analog components that are both notorious for hum.
I have the Grado Reference Sonata cartridge and an extensively modified Rega RP3 turntable.
 Now that I’ve got a subwoofer component in my system, I  hear the hum even at low volume, but only when I get close to the speakers.  Otherwise, I don’t know it’s there.
Is it compromising the final sound?  If so, is there anything I can do about it?
I just added some isolator feet to the turntable and it seems to be doing some good.
( I should probably forget about it, as the sound is wonderful anyway.)