Is it time to switch receivers?


I have the Yamaha DSP-A1 and someone tells me that I need something with HDMI to get true HD sound. Is it really that different? I would like to hear from those who have made the switch. TIA.
monterey
Am I upgrading or downgrading. I don't have much disposable income nowadays with a family and kids so I only have to spend what I can sell my DSP-A1 for. So far I got a $400 offer. Would I be foolish or smart to switch it to a receiver that has HDMI inputs? BTW, I'm running a B&K 200.5 amp along with my processor/receiver.
Does your receiver have 5.1 inputs? If your dvd player has the processing built in (like a Sharp BD20U), you can run the 5.1 output and you are good. Just run the hdmi cable to the tv for video.