I completely forgot to update this thread, but I heard back from Mica a while back per e-mail, and apparently this is a known issue with the Epic's electronics due to the lack of RF noise back in the 90's compared to now, and they're currently working on a prototype circuit that should fix the problem. According to Mica this circuit should be ready by the end of March/April. She also suggested that an orange capacitor could be soldered to the output jack to cut the extreme highs and thus the noise.
In the meantime I have come to the conclusion that my noise issue is probably being caused by the same problem Jazzyvee was having, i.e. noise induced by poorly shielded electronics in my house, since I haven't noticed this much RF noise anywhere else.
I've been able to make decent recordings of my bass by applying a 2k hz lowpass filter in audacity, which seems to get rid of 95% of the noise whilst not killing the tone too badly. Will be interesting to try the new circuit if I get the chance, but for now I can at least rest easy knowing the problem only (seemingly) occurs at home
