I set up an older Airport Express (MB321LL/A) at a friend’s house yesterday. He wanted to send his Pandora stream from his iPad/iPhone to his home sound system that feeds speakers located in six different parts of his house. I setup the Airport Express using the 2.4Band on his Xfinity Cable Modem/Router. There were several sound drop outs and even long periods of silence. While the distance between the Xfinity Router and the Airport Express was only about 20 feet, it sounded like a signal issue. Finally, during my troubleshooting, I changed the selection of the wireless network from 2.4 to 5 and the sound was perfect.
In my defense, this was an older Airport Express (era 2008) which I assumed did not have a 5GHz frequency. Then I found this on the Airport Express Wikipedia page:
An updated version (MB321LL/A, model A1264) supporting the faster 802.11 Draft-N draft specification and operation in either of the 2.4 GHz and 5 GHz bands, with almost all other features identical, was introduced by Apple in March 2008. The revised unit includes an 802.11a/n (5 GHz) mode, which allows adding Draft-N to an existing 802.11b/g network without disrupting existing connections, while preserving the increased throughput that Draft-N can provide. Up to 10 wireless units can connect to this AirPort Express. [https://en.wikipedia.org/wiki/AirPort_Express]
Even now I am wondering why the 5Ghz band would perform so much better due to its distance issues. I never would have thought that the streaming of fairly low quality sound would make such a difference also.