Airport Express or Devolo LAN adapter?

The Airport Express works great: it picks up a wireless signal from your router, and then you can run a short cable to the HDX.

I'm not familiar with Devolo, but it sounds like it uses the electrical wiring in your house to transmit the signal. Many people have warned that this degrades the audio quality of conventional amps, etc.

I think you need a hard wired ethernet connection between hdx and router. 15 meters of ethernet cable is cheap as chips. Is the routing (pathway) difficult? I've heard someone say the power plug lan adaptors work well despite others claiming such items pollute the mains supply.

If you are able to run the ethernet lead then this is preferable, trust me.

I agree that a direct connection to the router is best if feasible. If you simply need the ethernet to look up CD information, it doesn't make much difference, but if you will be streaming audio from another server on your network, wireless is unreliable, IME.

Of course, regardless of the connection to the HDX itself, it's nice to have wi-fi to run the Flash-based interface from a laptop.

I use devolo and it works great once you get the two adapters to connect as a network. No drop outs or any problems. When you first couple them on your computer its best to plug both adapters to the same extension cable, and once they're connected as a network you can remove them and place them anywhere around the house. The German technical support was superb.

I was a bit concerned about possible mains pollution, but I can't hear anything - and it also seems to draw minimal power. I tried an airport express but it just wouldn't connect to the router. I would have needed to buy an airport base station and possibly another express to boost the signal which would have costs over £200. Devolo cost me £40.

No cables. Not only because of the complicated routing in my current appartment, but also because of possible moving in the future.
Maybe a dLAN adapter like the basic 15 MBit Devolo (which even has a USB port besides the Ethernet port - could I stream music via USB and connect a USB DAC in the other room?) should be enough ...?

I use use the Develo d-link system and i am fully satisfied.It is very easy to install and you have a perfect dropless stream.
Just for testing i tried the d-link against direct lan connection and couldnt hear a difference.
Because my router is too far away from my hifi-system, wlan didnt work properly with my squeezebox.
My system is ext. HD>Laptop>Router>Develo adapter>Develo adapter>Squeezebox>Supernait. Controlled with Squeezebox Duett Controller