Can I connect an airport express to a time capsule?

I'm using an apple express now for my network router and have my stereo connected to it to stream music. I bought a time capsule because I needed the backup capability. Once I switch to the time capsule I'll lose the ability to stream music because time capsule doesn't support the connection to my stereo (audio out). Can I connect the airport express to the time capsule in client mode and use it to steam music? Time capsule is the router handling the wireless connections and the express handles the audio out - is that possible?