I'm hoping someone can help me troubleshoot a new piece of gear I purchased. I recently bought a used Marshall DSL40CR that was running fine, but just tonight the High channel stopped working. Low is perfectly fine, but Highstarted having a heavily muddied sound and now I'm hearing nothing out of it. All tubes are glowing, but I figured I'd seek out some sage advice before taking things apart and potentially making things worse.
As you have just purchased the amplifier and it is under warranty we would recommend that you take it back to the dealer it was purchased through so they can check it over for you.