Marshall DSL 15H problems -- how to proceed?

[quantumcat]

Hi guys,
I hope the topic hasn't been posted a thousand times or so but, I'm in a hurry and need to decide what to do.

Last week, I turned on my DSL15H and was baffled by the lack of sound. The power LED was on but just no sound. I tried the high gain channel and I could hear small amount of sound when the amp volume was all the way up. I purchased this amp new several months ago and have no problems up until now.

I've checked my cables, speaker, and other possible culprits outside the amp. Based on my limited research it seems that it is possibly a tube problem. More specifically a pre-amp tube failure..

1. Can I use a multi-meter to identify a broken, faulty tube?

2. I purchased at Guitar Center and to be honest, I'd rather avoid GC's "techs" . However, I was thinking of bringing my amp and testing tubes and purchasing it if it works. Anyone have experiences with this?

Thanks guys! Sorry if this is a constantly reoccurring question. I'm just in a hurry to diagnose the issue.

[Muziekschuur]

Do you have a multimeter?

Put it on beep and see if you speaker wire and instrument wire are ok.