Amp owners manual is wrong?

It says to bridge the speakers for using a single subwoofer.  I agree.  It says to run both RCA cords from head unit to amp.  I agree.  It says to put the amp in stereo mode.  I disagree.  I am only using one subwoofer.  Here is the diagram in the manual with my personal notes in color.  Am I right?  I hope you can read this attachment.

Sony EXM-302: 30 stereo or 90 mono, both 4 ohm settings driving a JL Audio 8W0-4ohm. I have another problem too.  In the same configuration (just like the manual, both RCAs plugged in - set to stereo - sub bridged) I put an inductor inline with the positive speaker wire, 5.6mH for roughly 110Hz lowpass filter.  Couldn't get much more than a whisper from the sub so I kept cranking up the head unit subwoofer control, ending at max (+15) and it smoked the inductor (literally - it's now black).  No damage anywhere else seemingly, amp still on.  I have two more inductors - never buy just one.  The inductors seem small like something for a circuit board, maybe 1/4" diameter copper wound barrel with a lead out of each end no thicker than a paperclip.  I would like to use the amp in mono so I can get more watts to the sub.  Just a little new and confused.   I am only looking for bass to fill in the sound, not for annoying my neighbors.

The other half of the install went great!  4-channel amp up front works fine.  Thanks for removing my goofy pic.

Wow, a 15 oz. inductor?  These teenie ones I bought might weigh 1/10 oz. 

Thanks DYohn, I just figured my problem out.  The frikkin subwoofer preout in my head unit (Alpine CDA-9847) handles the subwoofer crossover; I had no idea until I did a little Googling.  The manual does not state this specifically but I just hooked it up straight to the sub and it is playing fine.  I still would like to know at what frequency it low passes; must have been double-resisting the sub.  The amp never got hot so I guess it's extreme duty tested now.  Thanks alot; I'm gonna stop fooling with this and enjoy it.