usb to rca adapter?

Anyone know if there is such a thing available? I have an mp3 deck with an aux (xm, ipod, etc) rca input. I was thinking...If i had a cable which would convert a usb signal to rca's then i could play new mp3's through my usb pen drive as i rip them, without having to burn a new disk everytime. So much quicker and easier and cheaper. If an adapter like this doesn't exist already remember it was my idea!

thanks

USB outputs digital information, not analog audio, so there must be a converter (DAC) process.  There are several devices like this.  Sometimes Google is your friend:

Here's one, Here's one, Here's another one.

yikes... $50...

I suppose i can burn a lot of cd's for $50.

Do you think there would be any problems with the pen drive as the "driver" instead of a pc, as the part is intended?

Thanks again.