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) 


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.

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, 

So it looks like it is something to do with the balanced connection between the Classe pre and power amps? Repeat the experiment to make sure.
I'd post on their Facebook page if they don't get back to you.
The issue has not duplicated and after I started to unplug all connections and had the boxes out ready to bring in. On a whim I changed xlr cables and had all connections bare bone to play a source and it worked without issues. Re-hooked all to previous configuration and the issue resolved itself. 

Id just be curious to what the actual issue was. 

I was admonished no return call back from classe even to current with at least advice on which component to bring in and start a warranty process. 

Perhaps is due to their restructure but certainly keep that in my mind the next time I dump 7k on a preamp/amp combo 

I have to say I avoid amps with electronic gimickry like microprocessor-based configuration controls. It can't help.