XRGB-2 Stock AC adapter: What voltage?

[Darklegion]

My XRGB-2 ac adapter has been dead for a long time, so I've had to use 3rd party power supplies since.I have one that is a multi voltage switchmode supply, which runs at 13.8V both when under load and when not, but it tends to pick up interference quite easily.I bought a 13.8V unregulated power supply recently which doesn't have this problem but it actually puts out 18V when not under load, and 15.5V when under load.I'm just wondering if any one has tested the official psu to see what voltage it actually puts out when under load or not? I have a feeling that I actually tested the official psu a long time ago, and that it was a fair bit higher than 13.8V, but my memory fails me.
I seem to remember someone mentioning that the XRGB-2 voltage regulators can handle up to 18V, is this the case?