Which Digital SLR magazine? There is Digital SLR User, Camera, and Photography - three different mags.
If it helps, the biggest seller is Digital Photo which sells an average of 68,000 per month, then Practical Photography (from the same stable) at 56,000. All of the others are in the 20-30,000 bracket, some less.
The ones that are a bit different to the mainstream are Outdoor Photography, British Journal of Photography, and Amateur Photographer to an extent. They are also amongst the lowest sellers.