how to enable 5.1 sound output from a Mac Mini

As blogged ten days ago, I've been having troubles getting my new Harman Kardon AVR245 seamlessly integrated into my entertainment system.

My challenges included not being able to get a true digital output from my Mac Mini due to the optical cable (S/PDIF) plug incompatibility, not getting the Mac Mini to actually stream 6 channels of sound through the digital output nor being able to use the AVR 245's integrated HDMI switcher.

After a couple hours trouble-shooting today, I've got the system up and running with 5.1 outputs and integrated switching between the Mac Mini's HDMI out and the DirecTV HR20 HDMI out.

Here's what it took:

• Mac Mini digital output: the jack for Headphones/Audio out/Optical out on the back of the Mini is designed to accommodate a mini-headphone plug. If you think you can buy a standard S/PDIF optical cable to hook your Mini to your receiver, think again. You have to buy a separate adapter that'll convert the TOS plug to a minijack-compatible plug. Of course, Apple has a Belkin optical cable kit that has the adapter and will set you back $30 (and takes 5-7 weeks to ship as of this writing), but if you've already got an optical cable, why buy a whole new optical kit? You can hop over to Amazon and spend $1.65 (plus shipping) to buy a perfectly good TOSlink to optical mini adapter. Takes a couple days to get to you, but good luck finding the adapters stocked in a local electronics store (like Fry's). I checked several places and found I'd need to buy a whole "kit" just like the Apple online store is pushing. Adapter in hand, the Mac Mini now has an optical connection to the AVR 245.
• Mac Mini streaming 5.1 sound: I thought once I'd bridged the Mac Mini to the AVR 245 with an optical cable, I'd automagically get 5.1 sound from the DVDs I play on the Mac. Nope. It took a little digging but I found out how to coax 5.1 sound out of the Mini's DVD player (thanks to Dave's recent post on This Much I Know and related Apple Help docs). The default stream is a two channel stream from the Mini. To turn on 5.1 audio in Apple's DVD player, Choose DVD Player > Preferences, and then click Disc Setup. At the bottom of that window, change the Audio output setting to "digital out" and (very important) check the box next to "Disable Dolby dynamic range compression." Voila! Your DVD's 5.1 sound is now streaming out of your Mac Mini. This change to preferences applies to the MacBook, MacBook Pro and iMac, as well if you're using any of them as your DVD player for your TV.
• Integrated HDMI switching via the AVR 245: I'd previously thought that the AVR 245 was hard-wired to match an optical coax and an optical TOSlink to each of the two HDMI inputs. After digging a little deeper into the hundred page User Guide for the receiver, I discovered that I could override these default settings and match each of the HDMI video inputs to one the two optical sound inputs. Why does this make me happy? I can now get rid of the analog push-button HDMI switcher I'd been using to toggle video feeds to our HD TV from the HR20 DVR to the Mac Mini. I can now sit comfortably on the couch and use the Harman Kardon's remote to switch back and forth at the push of a button.
  

Next stop: 7.1 sound, but that'll mean adding more components to my A/V stack, and I've grown fond of the clean four-piece look we've got going now (HD TV, Mac Mini, AVR and HR20 HD DVR).