Denon Ext. In to Zone 2

Hello,
I almost have everything setup sound-wise with my HTPC and Denon AVR 687. I am running analog (no HDMI on my receiver) to Ext. In on the Denon. on Y cable to the front speakers and another running for the center channel (I only have front and center set up).

It was recommended that I use Ext. In for the best sound experience with my receiver.

The main reason I purchased the receiver some time ago was to run sound to an outdoor speaker (2 floors up, on the deck) which has worked great until my new configuration. I previously had an ipod dock which was the source for Zone 2. I have now removed the docking station so I can play any music on my HTPC instead of only what fits on the ipod. Since Ext. In is not an "input" on my receiver I am unable to select it (like I would for DVD, CD, VHS, ipod docking station, etc.).

I really hope I'm missing something obvious and I can push sound to the speaker but don't see an Ext. In option for output for Zone 2.

Appreciate your help.

One bump in case this was missed by someone with insight. Is it possible to run Ext. In out through Zone 2? Is this possible in other receivers?

Thank you

Thank you for the reply. I just have one source that goes through the Denon which is my HTPC. So I could run it through analog and loose the 5.1 channel setup. I guess my other option would be to buy a newer, used receiver. That would allow me to run HDMI sound through from my HTPC and I'm assuming I could also output sound to Zone 2 or similar to play from my speaker on the deck.

My other option might be to find some sort of splitter and run analog to Zone 2.