Same here.
Problem is (according to support) that there are no grounded external wall socket power supplys (the typical "wall wart") available on the market.
Yes, it's annoying if someone get's the player mainly for standalone use but i guess Kemper had in mind that most people will use the unit in combination with some kind of grounded equipment or at least plan to integrate the player into a pedalboard with (already existing) proper power solution. So from an economic point of view it makes no sense to supply a better (grounded + expensive) power solution per default as this would drive up the price of the unit for all customers regardless of whether they need it or not.
I got rid of the noise with a Cioks Sol - it's quite small, grounded and features excellently filtered isolated outputs. In addition you need 3 parallel adapter flex cables to combine 4 of the outputs into a single 9V @ 2.640 mA output (the included power supply delivers 9V @ 2.500 mA) which powers the player in the best possible way (original wall wart -> horrible hum/ buzz; Cioks Sol -> dead silence as it should be). Leaves you with one additional isolated output for another pedal (in my case a EAE Dude incredible). It's not the cleanest looking solution with the adapter cables but quite sturdy and still compact enough to fit in a gigbag together with the player.
If you need more outputs for other pedals then consider the Cioks DC7 + Crux - same performance im terms of audio quality/ noise level but a bit bigger and noticeably more expensive.