4.1 channels with Xonar D2X

I'm using a Xonar D2X connected directly to my amps via analog out.


I am running a 4.1 setup (Martin Logan Prodigy fronts, Aeon i rears, Def Tech subwoofer with Bryston amp). Unfortunately the D2X does not seem to support 4.1 setups. I have to choose either 4 channels (no LFE), or 5.1 (I don't have a center).


I managed to get 4.1 by setting D2X to 5.1, then configuring AC3filter to output to 4.1. Everything works fine.


Unfortunately when I use XBMC I don't get the center channel since it uses its own internal audio decoder.


So the question is: is there a way to configure D2X to 4.1 channels natively?