Will Adding A Consumer Home Theatre Subwoofer Compromise My Pristine Audio Quality? Options

[qusp74]

Hello Mac music fans,

This is my first post I have been a keen reader of the many threads that appear on this forum and I will take the time to thank all of you who contribute regularly, especially Mac Daddy and mortalengines,

I am a graphic designer/video compositor and animator running MAYA, Shake 4.1, Combustion 3 and Final Cut Pro HD.

I have been a mac user since the Mac plus primarily for design,photography and animation. Music production is a keen hobby of mine. I am the proud owner of
Mac G5 dual 2ghz 4gig ram with pair of (very heavy) 24" Mitsubishi diamond pro monitors
1TB SCSI raid
RME Hammerfall 9632 PCI with XLR breakout option with
Behringer ADA8000 adat interface for extra inputs and pre's
pair of KRK RP6 powered studio monitors
and here's the piece of kit the question is based on I picked it up cheap but haven't connected yet
A Welling powered home theatre SubWoofer
MicroKORG Synth/Vocoder
CME weighted controller keyboard
RODE NT2-A microphone

Also running the NI FM8, Kontakt, Massive, Battery and ARTURIA Minimoog, moogmodular, CS-80V Audio UNITS. as well as Waves diamond and Altiverb 6

I'm Currently running Logic express 7.2.3 (soon buying Logic studio 8 what a deal) for the production of both my own trip hop, IDM and electro mixes as well as pre-production scores and soundtracks for my Video projects. I have been only mildly disadvantaged by the lack of a sub in the past but I have been wanting one badly. I am currently paying off a lay-by on a KRK RP10S to match my fronts but I am currently working on a track that has a lot of bottom end for a competition here in OZ and was able to pick up the sub mentioned for $75 australian my question is;

Will patching the outputs of my RME interface through the sub and the associated high pass filters compromise the quality of the signal that reaches the KRK RP6's? or am i better advised to use the RME mixer utility to bounce the main output to another channel strip and a separate LFE output (adjusting the highpass accordingly)?

Thanks in advance for any replies excuse my relative ignorance

regards,
jeremy