USB sound card vs Onboard sound card?

[Minute]

You probably get questions like this a lot, and I did search through some threads here and some i found on google. But all of these threads talk about PCI/PCI-E cards vs internal, or those that mention USB ones do because they have no other option (onboard or otherwise).

So I want to know if there will be a noticeable improvement by using a USB sound card vs an Onboard one. I currently have the Zalman Theatre 6 headphones (5.1 audio), and am using the onboard sound card on my Asus P8Z68 V-Pro. I am considering either http://www.memoryexpress.com/Products/MX23989 or http://www.memoryexpress.com/Products/MX32117 Leaning towards the Zalman because it has a built in amplifier, but I'm not exactly 'sold'. I can't use a PCI/PCI-E slot, because the next available one is covered by me GPU.

EDIT: Also wanted to asked if an amplifier makes a difference in sound quality, I've read that most headphones benefit greatly from them.

 

[gamerk316]

Not really. Most USB devices use crap Digital to Analog converters, and that is one of the biggest factors in audio quality. Farther, most USB devices don't offer significant audio enhancements either.

Now granted, there are a handful of really HQ USB devices. The ASUS Essence One, for instance, is a stand alone DAC that can connect via USB. But most USB devices are crap.

 

[zander1983]

+1 for the Asus Essence One, but does not support 5.1 (I might be wrong here)

AMPs makes a big difference if you use high quality head phones

Don't get the Zalman, have a look at the Creative X-Fi Surround 5.1 Pro USB
http://us.store.creative.com/Creative-Sound-Blaster-XFi-Surround-5.1/M/B0044DEDCA.htm

 

[Minute]

The creative website isn't really working, every time I try to switch to the Canadian version of the site it goes back to the USA version. I really want to get it from them too, since its on sale with free shipping but the sites not exactly working.