A muso, according to one definition, is slang for someone, usually a musician, who is obsessed with the minutiae and technical details of music-making. Musos don't listen to music the way you and I do. When they hear the Detroit duo the White Stripes -- with Jack White on guitar and his former wife, Meg White, on drums -- they don't hear raw, bluesy stomps that announce the return of quality rock to mainstream ears. No, they hear a band that is missing a bass player. And they find this incredibly irritating and aesthetically wrongheaded.

Though Steven McDonald has been a bassist in bands since he was 11, he is more than a muso. Best known for playing with his brother, Jeff, in the Los Angeles punk and pop band Redd Kross, he is a clever pop-culture savant who has been playing for so long (he's now 35) that he has been unable to repress the muso growing inside him.

So several months ago he began taking songs from the White Stripes' latest record, ''White Blood Cells,'' adding his own bass playing, and posting the results, two tracks at a time, on his Web site (www.reddkross.com). In the wrong hands, the result, ''Redd Blood Cells,'' would be a misguided attempt to fix the White Stripes' music, but he knows there is nothing about the band to be corrected, only to be explored.

In many ways, this online-only album lives up to the dream that music fans originally had for the Internet. It is an example not just of a musician delivering work directly to his fans, but also of performers bending the rules for the sake of art. Mr. McDonald began putting these copyrighted songs online without permission from the White Stripes or their record label; during the project, he bumped into Jack White, who gave him spoken assent to continue. It can be that easy when you skip the intermediaries.