Spectral Dmc20 s2 blown up Please advice

Hi, am writing from Thailand

I've been using Avalon+Dmc20s2+(Dma90+Dma90, bridging)+Mit mi350/oracle v2 for a number of years. I got all the equipments from local dealer except one of the Dma90 where I had it ship from HongKong through Audiogon. This Dma90 I got from Hong Kong I would hear pop noise (high current running through the speaker I think) from the speaker each time switch the power on and with the power turn off i hear some short hanging noise but with the Dma90 I got from local dealer I almost dont hear that sort of noise. Again I have using them for years, one day I left the systems for a few hours and I hear loud boom on the left speaker(same size to HK amp). I traced the problem and found out the preamp was burnt. I open up the lid and see burnt on some optical protection circuitry(what i read in spectral page).

Please suggest what went wrong with the system and what caused the problem?
Is it a big blown up and can I get it fix in Thailand?

Thank you
Pic of optical protection circuitry
It could be that the preamp had DC at one of the inputs. If so. not good. My guess is that the unit will have to go to the factory.
wrong voltage as Spectral equipment are very sensitive. A 230V unit cannot work with 240V. The units from HK are 220V.