I'll offer a short list.

• The tape output is a purely analog device (similar to the second zone), so it only works with an analog stereo input. Any digital audio inputs will be unavailable. That means that when you're using any source connected with a digital audio cable, the tape output is effectively dead.
• The tape output is line level all the time, so volume level (with those analog sources that work at all) will be nonexistent. Thus, no way to properly calibrate and integrate the sub into the system.

These don't include the simple fact that the 950 is a product of the 21st century, with bass management capabilities that allow us to integrate a subwoofer without having to resort to this degree of "creativity."
That's right - but that's what happens when you tell the processor that all of your channels are "large." The processor trusts that you don't need the sub in those cases. Our goal is to reproduce sound in as accurate and balanced a manner as possible, which doesn't necessarily mean that every single driver in the system is active all the time.

Of course, there's also the next part of our discussion, which can change things somewhat (particularly for 7 Stereo)...
First, the "how." On the SPEAKER CONFIG page, just set "SURR" to "Small" and select either 40 or 60 for the "SURR XOVER."

Once you do this, the 950 will send a signal to the surrounds (side and back) that roughly starts at the crossover point and goes up from there (I say roughly because the crossover has a curve, it's not a "brick wall") while the signal below that crossover point goes to the sub. And this means that when listening to music in 7 Stereo mode, any material that dips low enough to cross that crossover point would find its way to the subwoofer output. And when choosing between 40Hz or 60Hz for the crossover, I'd lean toward 60Hz. That way, the Polks will be operating in a range they're really comfortable with rather than riding right on the edge of the point where they start trailing off naturally.

If you don't do this (which is what I was concerned about, and the reason I mentioned the possibility of steering audio below 35Hz to the surrounds in 7 Stereo mode), the surrounds and their Polk subs will get a signal that can at times go all the way down to 20Hz or below. The Polks simply can't handle that. That's why I am suggesting using a "small" setting for them.