found this off the Bossgtcentral ... quite an intro for the GT8 ... click on the Video demo for viewing ...
http://img3.musiciansfriend.com/dbase/media/flash/151422_gt8/index.html
ooh, and oso this article for those who want to know what's COSM means ...
COSM™ (Composite Object Sound Modeling)
Once a musical instrument generates sound vibrations, it reaches the human ear through various mediating objects, each of which significantly affects the sound. The material and configuration of the instrument, the electric /electronic /magnetic amplifying system, the air and reverberation of the room all affect the final sound. Sound modeling, the latest DSP technology, “virtually” reconstructs these objects. Roland’s breakthrough Composite Object Sound Modeling (COSM) uses the advantages of multiple modeling methods and succeeds in accurately emulating existing sounds, as well as producing sounds that have never before been created.
For guitarists, Roland's proprietary modeling technology known as COSM (Composite Object Sound Modeling) isolates and emulates all the various components in the signal chain, from the input of the amp, to the final vibration of the speaker cone. COSM then recombines these components to "model" the original amp's setup from tone stacks to speaker cabinets. Further, when these Virtual components are combined, they interact in the same way as the components in the original amp. This is VERY different from the static "snapshot" modeling techniques used by other manufacturers, which generally recreate the most popular sound of an amp, with no variations possible based on a player's performance or changes in the amp's settings. Roland was the first music company to introduce "modeling" technology to the guitar world back in '94/95 with the launch of the VG-8 V-Guitar system.
Here are just a couple of real-world COSM examples
1. When you turn up the volume on a COSM-modeled tube amp, not only does this increase the volume, but it also overdrives the virtual circuitry just like an original amplifier. The result is enhanced sustain, fatter sound, and you can even hear those virtual greenbacks breakup - just like the originals!
2. Turn off the EQ section (tone stack) and our COSM-powered VGA-series V-Guitar AMPLIFIERS shut down the sound just like the original (think Vintage Twin...)
3. Many early amps based on then-current technology were uneven in performance - not even all models in a given production year would sound the same. Current COSM technology allows for much greater consistency in our amplifiers- if its COSM, you will sound great out-of-the-box.