Volume normalization for 5.1 audio

[chrisr34000]

I'm having a a problem with my audio setup. I've used to connect my external speakers (stereo setup consisting of two speakers) to a USB DAC which was connected to the onboard soundcard (Realtek) of my computer.
When I played video files where the sound was encoded for 5.1 speakers, the voices were too low and other effects were way too loud. The Realtek card had a feature called "loudness equalization" which took care of this problem.
Now I'm using a Creative X-Fi Xtreme Music instead of the onboard Realtek, which doesn't have this feature in the drivers.
The question is now, how do I normalize the sound with the X-Fi? I want to use Media Player Home Cinema as a player, but the normalize feature there seems to have no effect. Is there something I can do normalize sound on the hardware end?
Thanks for your time and help
Chris

[enim]

may be short-cut to configure it for 2 channel stereo, i mean down mixing might help, if you do not have true-surround setup.

[hello_hello]

MPC-HC's normalize feature works for me, as long as I click on "Apply" after enabling/disabling it. It's not as good as compression though. If "regain volume" is checked, it works by dropping the volume when it hits a loud part, then slowly increasing it again till the next loud bit etc.

I use ffdshow for audio decoding with MPC-HC. It's mixer filter lets you configure the way multichannel audio is downmixed to stereo, or it has a fader which lets you adjust the volume of the centre channel easily.
I don't use it, but ffdshow's volume filter has a similar normalize function to MPC-HC, only it shows the amount of volume boost in real time. You can also adjust the volume of individual channels there too, although it might be wisest to reduce some rather than boost others.
The Winamp filter loads Winamp plugins, so you could try a compressor. I use the first one myself, but I've tried the second one and it seems to sound good while being very easy to configure. It simply has a loudness slider.
http://www.winamp.com/plugin/rocksteady-2-1/1099
http://www.winamp.com/plugin/loudmax-1-13/221811
You can re-oder ffdshow's filters by dragging and dropping them.

I'm not sure how any of that would fit into your DAC conversion though.