Problem: The max console resolutIon of any server via XenCenter seems to be 1024×768 @ 24bit. I wanted to increase this for my console as at times this is the only way to access it.
Solution: The consoles support 1280x 768 but only @ 16bit.
Advanced Properties of the Display settings > Adapter Tab > List All Modes > Select 1280 @ 16bit colour.
Seems this is as high as it goes.
Applies: XenServer 5.6 and 6.0
Thanks James. This has been very useful.