How much DME would that be?

Hmmm.... not sure... I've never brewed with DME. Malt Syrup, yes, but never DME. The last time I used extract to brew a "Belgian-ish" type brew I used about 3 cans (9.9 lbs) of Muntons syrup for a 5 gallon batch so it would be roughly 6 cans for a 10 gallon batch. I'd be tempted to use a can or two more to make sure the OG was around 1090 when it was time to put it in the fermentor.