Haven't heard the headroom but own a MF X-can V2 and a Creek OBH-11.
The X-can is a superb piece of kit for the money and is capable of withstanding many tweaks, such as power supply, valve replacement etc etc.
Thing is... "tweaks" cost money so you could face a lot of expenditure if you get "tweakers fever".
I am always trying to squeeze every last ounce of performance from my equipment to the stage that I no longer "enjoy" listening to the music like I used to years ago... these days I am listening for "differences" to sound quality that each "tweak" brings.
My advice to you is to use your ears as a guide.... forget what anyone else thinks... if the equipment and sound makes you come out in goose pimples then it's the right stuff for you!
I'm too deeply into listening to the components that I have forgotten the joys and emotions real music brings but I think I can safely recommend the MF X-cans to you.
Don't change the valves, don't upgrade the power supply, don't encase the X-can in epoxy resin, don't cryogenically suspend it and don't encase it in concrete. I believe superb results have been gained by simply plugging it in and "listening" through it.
I'm off to prepare some epoxy resin... according to a friend the X-can produces a more spacious soundstage and 3 dimensionality if its encased in a 3 metre square block of epoxy resin... I'm going to take it a bit further and add some pasta into the resin and see if makes Italian opera sound a bit more realistic.
Pinkie