This gets interesting.. I have a dual Maxxy and QM2000 and did not have to build anything at all !!! and it works just fine.
Its some months since I did that so I'll have a look and see what I did, I dont recall any problems ??? weird
Because the output of the QM2K is a "balanced out" with some "smarts" it may be possible to reverse the output. Like Ground pin5 and use pin 18. HOWEVER I suggest a quick email to Hayden at Pangolin (before doing this) he will almost certainly have an answer for you direct from the horses mouth.
Get back to you after I have looked at mine.
Cheers


Ray
NZ