Sound card's maximum volume half of onboard's

Hello. I'd just like to add that I am new here. Hello. I've posted in other hardware forums for years. This is my first time using Toms hardware.

I recently added an Audigy 2 ZS to my system, using very capable and powerful Edifier S550 5.1 satellites.

Previously I used the onboard Realtek audio, which provided OK audio quality, and had an exceptionally high max volume. Sound quality deteriorated, though, at high volume.

With the Audigy 2 ZS, the sound quality is EXCELLENT, but I cannot get volume even half of what the onboard audio gave.

Why would switching to another sound card affect the volume levels? The speakers I am using are amplified.

I need high volume for a dance competition I am hosting on New Years Eve and I'd love it if one of you could help figure this out and let some strange folks from half way across the world have the fun night they deserve. Any lightbulbs?

UPDATE

Since posting, I've tried disabling onboard audio in BIOS with Creative drivers uninstalled. Maximum volume was now working perfectly.
I then reinstalled the Creative drivers, and the volume was back to where I started.

I conclude that there is something wrong with the Creative drivers that is causing the volume problem. I can't find anything in support. Or anything in any forum with this issue. Drivers are fully updated.

UPDATE

I changed the format in speaker properties from 16 bit to 24 bit and the speaker volume enhanced significantly, but the sound quality lowered. I'm not sure why changing the sampling rate would do anything, but it did. I am still looking for a better solution.

UPDATE

I decided to use custom drivers and it solved the problem. F U CREATIVE! Here's the link for anyone looking for the solution: http://kxproject.lugosoft.com/

Thanks for the help, Tom's Hardware!