I bought a DSL 401 as at the time it was the smallest (i.e. lightest) valve amp that Marshall did. It has three channels and the clean and crunch tones are superb. It is well loud enough to do a gig but you can get the tones at lower volumes so it's suitable for home use.
Marshall however do not do an extension cab for it and I wanted one to gig with. After a bit of research I discovered that the now discontinued JTMC 12 cab was a perfect fit. Even the holes for the amp feet are in the right place although the colour of the covering plastic and grille don't match.
I eventually found one on Ebay but the speaker didn't sound right so I replaced it with the same one as in the amp and Hey Presto! The difference in a gig environment is wonderful. The sound is bigger and rounder.
Iv'e owned this now for 6 years and not even had to replace a valve yet. The only slight complaint I have is the reverb is not brilliant but if you're in the market just try one out.