I'm stumped.

I just installed an Airport Extreme base station (802.11n w/ GigE) and three Airport Express base stations (802.11n).

The three AExpresses are simply running Airtunes and do not extend, repeat or bridge the network.

The problem I'm seeing is that data rates are terrible. I'm getting a good signal, and theoretically, everything should work fine, but data rates are just rotten and I can't figure out why.

The weird thing is that the data rates are good enough to run Airtunes without any stutter or gapping in the music. If the network was screwed up, then I would assume that all data transmission would be equally bad.

I'm using a MacBook Pro w/ an "N" enabled built-in Airport card for my observations. The data rates are equally poor whether I'm sitting in front of the Extreme or in another part of the house and noise on the network seems to be within acceptable levels throughout the house.

I've tried moving back to the 7.3.1 firmware for all the devices, but the problem persists.

I've tried different channels, changing to a pure "N" configuration, moving to 5ghz and toggeled both Interference Robustness and Wide Channels, all to no avail.

Data rates when I'm tethered are awesome, so this isn't a WAN issue.

I should also note that my Linksys G router always performed flawlessly, so I'm skeptical that the environment might be a source of interference.

I'm stumped.

Does anyone have any ideas? I really don't want to call Apple on this one - I think it would be too painful!