Don't worry Audrey, it doesn't make a bit of difference what power output the external amp/speaker system has -it will not damage your KN7000
Unless of course, you have 20 Kilowatts per channel at full blast and it shakes your keyboard to bits

Logitech Z2200 Spec.
Nominal Output Power (Total): 200 Watt
Max (RMS) Output Power (Total): 400 Watt
Media Included Qty: 35 - 20000 Hz
Audio Amplifier: Integrated
Connectivity Technology: Wired
Speaker System Details: 2 x right/left channel speaker - 40 Watt ¦ 1 x subwoofer - 120 Watt
Remote Control: Remote control - cable
Manufacturer Warranty: 2 years warranty

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Willum