does this only occurs when u use your DIY speaker cable?
is the speaker cable use create is using multiple cat5? how long the cable?
If IT ONLY HAPPEN with your DIY cable then the possibility is that...
1) your multiple twisted speaker cable have too high capacitance and create osilation
2) check your twisted cable, is there mix cable between positive and negative? (if u are using the twisted 27pair, u may mix them...i had done the mistake once)
I have only this speaker cable...i dont have any other speaker cable.
I have used copper Teflon wire 14AWG plated with silver. The cable is created by using a total of six wires ...3 positive and 3 negative. I braid three wires into one and used for positive and negative. then i twisted both the braided wires like twisted pair.
I can't figure out why the hum is greater in the evening.
I suggest you to untwist the cable.
That is do not cross braid the wires. Let the positive and negative wire run parallel, and test the result.
Twisting or cross braid may create a lot of capacitance and make the amp unstable.