Occasional no audio on 2-channel system

My system includes a CD player, a preamplifier, two monoblock amplifiers, and two Martin Logan electrostatic speakers. The system occasionally has NO audio sound, or only in one channel works sometimes, and then one day they work like a champ with no issue. This drove me insane because I don't know what the problem is. I have tried to identify the problem, but could not, any advises would be very much appreciated.
What's your system?

First guess: If you sometimes have no sound at all, it likely isn't the monoblocks. What are the odds of both amps failing at the same time?

These intermittent problems are hard to debug. You'll likely have to switch a lot of things around, and then wait for the problem to appear again. If you have the ability to swap in a different CD player, a different preamp, etc., you might get somewhere.
Check all your connections first.
Its likely that your speaker(s) are plugged into an outlet that's not on the same circuit as the rest of your system. Its also possible that those outlets are connected to a wall switch. You may think you're turning out a light, or some other appliance, and not realize you are turning off a speaker. Also, its fairly common to connect a wall switch to just 1 plug of a 2 plug outlet. It can be deceiving if you're not aware of it.
Depending on how old your Martin Logans are, ML uses a "auto-on" feature that senses an incoming signal and turns the speaker on. If there isn't a signal, the speaker shuts off. ML does this because once the electrostatic panel is charged, it attracts dust, so if the speaker is inactive, this eliminates that problem.

ML did have some issues with this circuit. You might need to talk to ML service.

I agree with Rhanson that you will need to start more or less from the source and work your way through the rest of your system, replacing each component until you track down the problem. Although in this case, I would start with the speakers first.