Speaker hum

With speakers that efficient and an amp with a ton of gain, you’re likely hear the slightest hint of residual noise, coming from anywhere in your system. Why did you mate speakers that sensitive, with an Odyssey Stratos amp?

I discovered a light dimmer in my room was the culprit.

Make sure your TV cable coax is not the culprit if using in an AV system. 

I cleaned up everything behind my rack and made sure the power and source cables don't intersect at all.  Unplugged everything from the preamp and when I remove just one channel between the preamp and the amp it stops. It seem a little louder now and you can hear it at a 4 or 5 feet.

I have a cable hooked to the cable box to the AV receiver that connects to the preamp for using the mains for the front channels in a HT bypass in a 5.2.

The outlets feeding the system are straight from the breaker panel, nothing else on the circuit, but I have 3 different light switches with dimmers for LED lights in the room on their own circuit.

I didn't know that I was shooting myself in the foot by pairing HE speakers with the Odyssey amp.

I have experienced hum from dimmers even when speaker cables were disconnected at the amp and the conductors twisted together to simulate the output impedance of the amp,  close to 0 ohms.  Fixed it by installing twisted pairs for the cables similar to professional speaker cables from Belden, Mohawk and others which reject common mode noise.