USB

Universal Serial Bus (USB) is a serial bus standard to interface devices. USB was designed to allow many peripherals to be connected using a single standardized interface socket and to improve the plug-and-play capabilities by allowing devices to be connected and disconnected without rebooting the computer (hot swapping). Other convenient features include providing power to low-consumption devices without the need for an external power supply and allowing many devices to be used without requiring manufacturer specific, individual device drivers to be installed.

Just another bus but a very popular one. It inspires a lot of people to make all kind of products.

 

When the computer sends the audio stream to an USB port, the CPU first reads the data from the hard disk and caches blocks of the data in memory.

It is then spooled from memory to the output port in a continuous stream.

This can be done in three different modes.

Drop out.

Some users complains about drop outs when playing USB audio.

There are also claims that there are differences in sound quality using different ports.

This might be due to different devices sharing the same USB-Hub.

If your audio and your graphics card are on the same hub, the bandwidth required by the graphics might cause the audio to stutter.

It might also generate jitter.

 

Solutions

• Using another port for your audio might cure the problem.
• You might try the windows device manager  and see if you can configure a usb-hub in such a way that it is used for audio only.
• Upgrading to Vista might be a easy solution as Vista not only has better audio, the USB drivers are said to be improved also.
• A simple solution is to buy a PCI to USB card. As it is PCI it gets 1 exclusive interrupt. Use this one for USB audio only and the audio device can get 100% bandwidth.

More:

http://www.audioasylum.com/cgi/vt.mpl?f=pcaudio&m=33658

http://www.audioasylum.com/cgi/vt.mpl?f=pcaudio&m=33930