Random High pitch & Horn Sound took over my system! Classe CP800 & CA-D200

Hello all, I was hoping to get an answer here for maybe bringing my unit in for service. I have fixed the issue but have no idea where it came from.

So.. I have the TV on... all of the sudden, I hear some sound interference & no more audio, only a high pitch at low volume getting louder and louder to where I rushed over and turned everything off. It sounded like a Siren. Only the same audible noise. Almost like that emergency broadcast noise. 

I shut everything down, unplugged, allowed capacitors to drain.. plugged in and same thing. Kept doing this, noticed the level of the noise was lower but the issue still there.

I did notice it hit my Sub first - then carried over to my 2 main front channels. (I think i can recall a thump or pop in the sub) 

I could not get this problem to stop - Even went so far as to attempt to re-flash - reprogram both amp/preamp via USB firmware (although this wasn't the issue.. i was in desperation mode)

So I loaded up boxes and was prepping to bring both my pre-amp and amp into service because I don't have another amp or pre-amp to try out (trail and error) within a 60 mile radius. 

I then decided... let me swap out cables. 

I removed my 2 balanced cardas cables to my amp and interchanged with analog RCA. This was after I disconnected everything  but left my CD player hooked up (digital XLR) 

and...

voila. I have amazing sound again with no issues. 

I shut everything back off and re-hooked up all original cables.. Ill be dammed.. its like the issue never happened. 

.... I called Classe tech line to try and see what the issue is/ what it maybe/ will it happen again? When it first happened my initial though was dam this is going to blow my speakers (got that loud before I shut it down).
I have not gotten a call back from them to discuss.

I am, worried it may happen again and blow out my speakers when I am away on business and the wife is using it... 

Has anyone had this experience or can lead me to the possible issue? I do believe it was my pre-amp if I were to guess.. I had removed my amp out of the equation, tested and could still hear the issue in the sub-woofer prior to the voila magic... all working again.

System.
Classe CP-800 Preamp
Classe CA D200  (2 channel digital amp) ((Cardas XLR & Cardas Speaker wiring)
Classe CDT - 300 Transport (with Transparent Digital XLR)
Furman Line conditioner (Upgraded Transparent Power Connects through-out)
B&W 805D3
B&W ASW 850 

Using only 2 optical digital connects for a AT&T Cable Box & PS4.

I will mention... at my current setup I am using a shared circuit on #14GA however nothing else was in use during random event..  I have not had time to pull a dedicated line to the system but I don't think the issue is here. It is properly grounded. 

Thank you,