Possibly, but sometimes the LFE can still introduce a high impedance signal that may actually end up causing a large volume drop when you play your 2 channel setup. That can also be a bit messy in terms of material delivered from potentially two difference sources. My recommendation would be to run XLR from your Setllar Gain Cell preamp to your S300 (if you are not already). Then I would run the RCA preouts from your Stellar Gain Audio and the LFE (subwoofer) preouts from the Denon 4300 to a RCA switch box. From the RCA switch box, you can run that to the STF-2 and VTF-2 Mk5. That way you can select that source that you want to go to the sub. When you use your 2 channel stereo only setup, you also want to set the crossover to in on both subs as well. For HT, you can set them to out because the denon has a built in crossover for you.