No sound with just HDMI cable

I am still relatively new to the world of high definition and I've been looking for an inexpensive solution for my bedroom. So far, I've managed to turn my bedroom into a decent mini theater using inexpensive equipment. I am looking to upgrade in the future to better surround speakers but for now I'm content.

Ok, my question is do you have to use either optical or digital coaxial cables for your audio in order to use DD,DTS,etc.?

The reason I ask is because the fellow who sold me on an AVR told me I only needed to use the HDMI cable for my audio and video. It sounded so easy and I was thrilled because I had a few extra HDMI cables that I got for under $10 each. Once I connected everything, I noticed that I wasn't getting audio...just video. I was frustrated to say the least, especially after hooking up a PS3, a wireless blu-ray (for netflix), a dish DVR, and an old 5.1 sound system (added a new subwoofer because I needed the composite cable hookup). It just seemed to easy. I don't know any salesperson that wouldn't try to sell you on those overpriced cables, especially if you really needed them to run your equipment. Naturally, I wanted to have it all hooked up the that night, so I ran over to walmart and scooped up a couple of optical and a digital cable to run my equipment. Everything is good now but I'm still confused to whether or not they were needed. I kept all the receipts and didn't damage the packaging for the cables just in case I don't really need them. The receiver I'm using is a harman/kardon AVR 154, if that helps any.

You need to read all of your manuals. It sounds like you have audio over HDMI disabled.

I'm pretty sure the HK 154 is limited to HDMI video switching. It will feed audio over HDMI to your TV, but it won't process HDMI audio itself. That's fairly common with the least expensive HDMI receivers. The manual will say something about needing a separate audio connection.

The salesman was correct about HDMI in general. But, it looks like he wasn't familiar with the capabilities of your particular receiver.

Thanks for the responses. You are correct BIslander, this particular model doesn't process audio through the HDMI output. I found a customer review on this particular model that pointed this out last night. The salesperson at BB just wasn't familiar with this receiver, obviously. It's all good, I got a great deal on it at $192 new...well after the optical and digital cables, it ended up costing ~$250, which is decent for a entry level receiver, iMO.