DxM is one of a chain of quite ridiculously stylish coffee shops in Sapporo run by Morihiko Coffee. These include the beautiful cafe converted from an old wooden house in Maruyama (which I cannot recommend highly enough, even if it is so small it's hard to get a seat a lot of the time) and Atelier Morihiko on the street-car line in West Odori, where I once had an almost transcendentally delicious pear tart. Seriously, I had no idea anything made with pears could be that good.
DxM's concept is to pair the same amazing coffee that Morihiko serve everywhere with luxurious doughnuts by David (which is, I think, a bakery rather than just some dude named David). The coffee is wonderful and the doughnuts are really fancy, expensive doughnuts. And of course the interior is just excessively stylish, a minimalist collision of industrial trappings and an old school house. That makes it sound a little messy, it's not. The place is a gorgeous combination of metal and wood, and it's not until you look at the chain-link fence and industrial lights, then notice the blackboards and school desks that you realise they've gone for some crazy factory/school approach. But not scary and fascistic like Pink Floyd's The Wall. Y'know, the cool industrial schoolhouse approach.
If you like super-stylish, somewhat expensive coffee places then you have to pay the place a visit. I don't really have a whole lot more to add, except to reiterate that the coffee is really good (they roast their own coffee, and note the hourglass they gave me showing how long to let it brew before pouring it) and that the doughnuts really are fancy.
To be completely honest I don't need my doughnuts this fancy, and just nice hearty Mister Donut doughnuts are fine by me, but it was certainly no hardship at all to eat these ones.
It's pretty close to Sapporo Factory shopping mall and I would guess that the closest subway station would be Bus Centre Mae on the Tozai line. Perhaps a fifteen minute walk from Sapporo Station? Let's say so. I'll put it on my map, so go and try the place for yourself!