This is a gigantic PITA. I can't believe some people still think proprietary software has good support for proprietary hardware - Even with a relatively simple setup like this, many hours of searching forums, installing and reinstalling drivers, fiddling with the BIOS and sound settings still hasn't produced any sound.

  1. Upgraded the A/V receiver firmware (Update: sorry, the link is dead). This was easy since I've connected it to the Internet. It's now got the latest firmware.
  2. Installed, removed and reinstalled the latest video driver - Catalyst Software Suite 12.8 (Update: sorry, the link is dead). I rebooted after each step.
  3. When I plug in the HDMI cable, a device called Generic PnP Monitor is added to the Devices list. I know it corresponds to the A/V receiver, because it is removed again if I unplug the cable. This messed up the dual-screen display the first time I plugged in the HDMI cable, making only the secondary display active until I managed to move the Catalyst Control Center window from the invisible desktop to the visible one.
  4. Tried to update the driver of the Generic PnP Monitor, but it just says the driver is up to date.
  5. In the Sound → Playback window the AMD HDMI Output playback device is enabled, but it shows simply Not plugged in, so I can't configure it or set it to the default, as some forum posts instruct.
  6. In the BIOS menu there is a setting called SPDIF OUT Mode Setting [sic], with possible values SPDIF and HDMI. It's set to SPDIF, according to this cryptic description: Select the [HDMI] option only if you have a video card with HDMI support and are using the SPDIF signal for the high-definition monitor's speakers. I'm not using monitor speakers.
  7. In the Screen Resolution window there's a TX-NR509 device. The resolution and orientation can't be set, and I've set Multiple displays to Disconnect this display.
  8. The A/V receiver shows that it's connected, but not receiving a signal.

In conclusion, both devices know about each other, but Windows 7 seems to think the A/V receiver is a monitor. Any ideas?