It's indeed a bit of overkill i guess. As you'd need 6 outputs per panned audiotrack of your DAW. Ouch! Is gonna cost a lot in D/A convertors...
You best look out for a mixing system which has 5.1 panning. I know www.tonelux.com
has units for this, but i'm not sure if the system also actually sums, or if they are more like mixerchannel strips which still need a summing bus. Paul Wolff hopefully jumps in to clarify.
If they don't sum, you can still look for a summing system like Folcrom to sum each of the 6 surround channels which are outputted by the mixerchannels. But at least you would have saved a lot on D/A convertors.
For example: Say for 16 DAW audiotracks, you'd now need only one DA16x (around $3000, Apogee taken as example as it's prolly one of the cheapest solutions), instead of six (around $18000). Saves you the hassle hooking them up, and also $15000, from which you'll have rather some money left even after buying a system like Tonelux (or similar).