Windows 7 - Realtek high definition - bad sound quality

I just bought a Gateway laptop (Win 7 64-bits) with a Realtek high definition. I listen a lot to classical music and I am disappointed with the sound quality of the card.

I listen the music with a good Seinheiser headphone. The problem is not the headphone because I switched back and forth between the new laptop and a 6-years old Compaq desktop and the desktop sounds much better. On both computers, I have the equalizers set as flat and no audio effects.

The problem on the laptop is that the sound sounds "muffed", with no treble and no color. I checked the drivers and they are the latest.

I am pretty sure that this is a good quality card and the sound should be good. What should I try?

Thanks,
Tom

Have you fiddled with the settings in the Realtek HD audio control panel, as shown below?

I'd turn off any special effects or enhancements to begin with.

I just began using Realtek myself, but have not done any critical listening yet to decide if I like it or not.

Yes. As I mentioned on my email, equalizer is flat and no special effect.