Taking a wild stab at things here. You are going from RCA outputs on the WeGo (which are unbalanced) to the sub and then to the full ranges (usual hook-up)?
If I found (with trouble) the right speakers, the sub has satellite out (2x 500W) and line in/line out on RCA’s ONLY!
There are several things amiss with this (apart from the quality of the components).
1) There is NO way to run a balanced cable to the sub, as there only RCA’s, no XLR or balanced jack inputs. Running an RCA-RCA cable for anything over a certain length is not a good plan. Running an RCA-RCA cables straight into your PA is even a bad plan. You can fix it by buying two boxes that allow you to connect an RCA output and an RCA input with a balanced cable in between. But that is throwing good money after bad money imho.
2) The built-in crossover in your sub most likely ONLY works when hooking up the passive satellites. The RCA’s I am guessing are parallel connections. So going stereo to your sub (RCA) then single RCAs to left and right speaker will introduce more places for hum/buzz and signal loss. Also your full ranges will receive the full range signal, not the signal without the sub low (<200Hz). Meaning that an important feature of using a sub with crossover, to give you more power for the low-mids and mids, is lost. More than that, the balance towards the low end will be seriously skewed as you now have your 15″s firing the low stuff AND the sub. Not what you want to happen. You want the sub to take over that frequency field and free up the space so your full ranges can do their thing better, making for a better overall sound.
Frankly, I don’t know what to tell you. The boxes I mentioned will set you back 50 bucks a piece and you’d need 4 of them (one for the WeGo, one for the sub and one each for the full ranges), which I think is ridiculous money and extra cables, power adapters and what not to make these speakers work.
You seem to have the wrong set (it would be better to have two passive tops with this sub to use as satellite) and the speakers don’t allow for a hook up that will most likely guarantee humming/buzzing free operation. While I don’t know this particular brand, I do have quite a bit of knowledge of this LEVEL of brands and it is safe to say that they are not putting too much money into quality components, let alone serious R&D. I have known stuff like this humming like a bird with only power hooked up and the amp on, no signal cables, nothing. And even if (semi)silent when not hooked up to signal, plugging in an unbalanced cable can introduce the problems you are describing.
A power conditioner, while a handy tool especially in areas with not so stable power supplies, has no effect on reducing humming/buzzing effects. The only thing you CAN try to get rid of the humming is having all your gear on the same group of outlets. You could try making this work by using only one wall outlet and then running extensions cords. This may or may not work depending on what else is on that group. You might end up blowing a fuse.
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