I'm not sure what you're asking...you want to connect a dac directly to an airport express?
You could just buy an airport extreme which connects wirelessly to your computer and plug into it an external hard drive if you need one. Then the music streams wirelessly to your computer which then can have a USB dac connected to it which in turn connects to your integrated.
You can get a USB Benchmark dac-1 (small footprint and nice headphone jacks) for your price new (I think if you look around) or certainly used.
You could just buy an airport extreme which connects wirelessly to your computer and plug into it an external hard drive if you need one. Then the music streams wirelessly to your computer which then can have a USB dac connected to it which in turn connects to your integrated.
You can get a USB Benchmark dac-1 (small footprint and nice headphone jacks) for your price new (I think if you look around) or certainly used.