Yes, install multiple DNASs and use multipel sources.
Check out the Sticky post titled:
SHOUTcast: Important Info & Answers to FAQs. READ ME!
Scroll down a bit and look for the section titled:
How to Setup a Live Audio Stream -> Multi-bitrate Streams
Follow the muliple DNAS setup instructions above.
Then, either use multiple instances of the Winamp/DSP combo or install multiple copies of the Winamp/DSP combo.
The former is set via:
Winamp -> ctrl+p -> General preferences -> Allow multiple instances.
The later is set by installing Winamp and the DSP in multiple directories.