Update!
So the optical-coax converter arrived yesterday, and after realising I did not have the right toslink cables and a quick trip to Maplins I'm pleased to say it's up and running. It is fed by the optical output from the Modright into the Dual Core which process in digital, and then outputs optical to the adaptor which then feeds co-ax to the 6ks.
A quick typical calibration with the microphone positioned where my head normally is demonstrated unsurprisingly that the room is inducing a big spike at 50Hz followed by a suck out at 100Hz. The auto algorithm flattens it all out and I stick a few bass heavy tracks on hear the effect - Trentemoller, James Brown, Augustus Pablo etc.
The first thing I have to do is turn it up, and that no longer induces a fat bass rumble. The sound is cleaner and the bass sharper, bit ore depth, and certainly a fair bit more detail. Pressing the bypass button lets you quickly A-B the non EQ'd room response, and its effect is pretty stark. At first it sounds like the non EQ is weightier and richer but after a while your ears just know which version is right.
More listening tomorrow but so far jolly good!