QB8 mk2 European schuko version.
I had several demonstrations (shop and home) of the QB8 (mk2) and came to the same conclusion each time - I bought one.
To my ears (and against my skepticism) it tightens everything up even using ordinary "kettle leads" - more precise imaging, better dynamics, tighter bass, more air to the treble... Adding Frey 2 power leads takes the improvements further - I've bought four and will be adding two more in time (unless I get two Tyr 2 instead).
I recently had a demo of the QX4 - love at first listen! That's right, I bought the demo unit.
My advice - listen...
... but only if you can afford to buy
I now miss the QB8 in other systems!
Get the QB8 first and use the power leads you already have.