I guess it depends on the quality of the keyboard/speakers. I have heard that keyboard speakers, such as my 1000, have a tri amped system, so the sound is much more detailed than regular monitor speakers.

That said, there is the Multimedia speakers that propose a tri amped feature.
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Yamaha 920 / Yamaha DGX-670 / Maui 5 Go (2) / Senn e935 / Sony C80 / Tascam DP24sd / ATEM Mini Pro switcher (studio)