[racket] Trouble with RSound

Hello,

I'm trying to use RSound, but I ran into a problem. Thing is, if I try
to play more than one sound, in any manner, during a single racket
session, I get a "pa-open-stream: Device unavailable" error. This here
is enough to trigger the problem on my machine:

#lang racket
(require (planet clements/rsound))
 
(play ding)
(play ding)

For what it's worth, here is some info about my system:

Fedora 17, x86_64
Racket 5.3
portaudio v19 (from Fedora's repo)
RSound v4.4

Thanks in advance.