I have A Marshall DSL 100H powers on but has no output sound. I bought amp in Dec 2019, bought it brand new. all was well for about 6 or 7 months then it made a popping sound with a loud hiss and went quiet, I have many different heads so I let it go for awhile. I'm trying to find out, what the common problems of this model of Marshall are. I'm new to the forum and would greatly appreciate any help or advise. if these heads have had a history of certain failures, that's would give me a starting point other than the tubes, fuses, and pots. I can find no shorts everything looks normal, has anyone seen this in this model????