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