With just a Raspberry Pi and a few additional components, you don't need an expensive KVM to reap its benefits ...

Figure 2 TBH principle sums two 8-bit PWM signals in one 16-bit DAC = Vref (MSBY+LSBY/256)/256. The asterisked resistors are ...

You can use it to adjust volume, smoothly scroll documents and web pages, or quickly search through videos.