Sony DVP-NC685V, bass management, preserving hiRez

I went ahead and bought this universal player because of the plaudits it received in TAS for it's SACD playback. It has 5.1 analog outs and re-assures one everywhere in the manual that the hi-rez frequencies are preserved if these outs are used. All of the PCM circuitry is isolated and sent thru the digital and coax outs. Here's the problem: I can't plug my sub into the .1. The manual states that if I select no sub, or don't plug one in, the .1 is redistributed to the front mains. To you techies out there: Does redistributing the .1 enable the PCM circuity that will covert the hi-rez back to 48kHz/16bit, or is another type ciruitry used that doesn't degrade the hi-rez signal. The manual is unclear on this. (I've asked Sony too, and will report if they answer.)