I recently got a blackface Walkabout head. Before I purchased I called Mesa, wanted to know if the design had been updated to include Speakon jacks and a pre/post switch for the DI. I was told that the speaker jacks were still 1/4 inch but the newer Walkabouts did have a pre/post switch on the DI. So I placed an order, got my amp - no pre/post switch!
Called yesterday (coincidentally, right after Chef's post about it) and spoke to someone else at MB and was informed that the Walkabout is the only amp in the current MB line that doesn't have a pre/post switch for DI. Evidently the person I spoke with the first time had been mistaken. As it is right now, even changing the master volume on the amp will affect the signal going out the DI.
However, I was told that Mesa can mod these amps to add a pre/post switch which would tap the signal right at the input stage. So essentially, that would net the same results as using an external DI before the input jack, albeit with a level control (the DI level control would still be active). I haven't yet decided if I'm going to opt for the mod...
I'm using my Walkabout to power either a pair of Berg HT112ER's or a pair of Baer ML112's. It kills. I really like this amp and consider it to be the best of what's out there right now in smaller, lighter weight designs.