Multichannel Unprotected Audio Over HDMI

I have implemented a digital crossover network in my PC. Depending upon configuration, it can input two channels and output as many as eight. I want to send the eight output channels of LPCM to an AV receiver via HDMI. This is totally unprotected audio content -- it may come from CD, in which case it was originally 2 channel 44100 Hz, or from A/D converters, in which case it was 2 channel at whatever sampling rate I choose.

I have installed a Gigabyte HD 4350 video card along with the Realtek 2.23 HDMI driver. The receiver is a Yamaha RX-V465. No matter how many channels I attempt to send and no matter what sampling rate, the receiver always reports the signal format as 2-channel 48 kHz LPCM. I can listen to the "front" channel outputs on the Yamaha, so audio is definitely being passed. The receiver just doesn't recognize any of the other channels.

What do I have to do in order to send 8 channels of unprotected LPCM over HDMI with this hardware? Is there some hidden configuration parameter that I have failed to set?

OS is Windows XP sp3; crossover is implemented under ASIO4ALL (WDM-KS).

Thanks.

Answering my own question, so that perhaps someone can benefit in the future:

The Realtek HDMI audio driver [http://www.realtek.com.tw/downloads/downloadsView.aspx?Langid=1&PFid=24&Level=4&Conn=3&DownTypeID=3] is only for use with Vista. Even though it will load under XP, it will not work.

For XP, use the ATI HDMI audio driver [https://a248.e.akamai.net/f/674/9206/0/www2.ati.com/gamesite/9-4_xp32-64_hdmiaudio.exe].

Sorry for the cut-and-paste URLS, but my post count is too low to allow embedded URLs.

Yes, it works. Only allows 44.1 kHz or 48 kHz, 16 bits, but it works. Given that my source material is 16 bits, it's not a problem.