WieWaldi The setup that uses the integrated usb audio looks like:
- Piano sends USB-midi to the laptop
- The laptop runs VST which generates audio signal
- The laptop sends the audio signal back to piano with USB (with the same cable)
- The piano plays it via headphone or integrated speakers
This works with the Roland.
If you add a powered USB hub in between then the same usb cable also charges the laptop/tablet. (Or in Kawaii's case the piano can also provide power. Although I don't think the Kawaii had enough power for a laptop. Though it would charge a phone or tablet.).
There is no lag I can notice with that setup. But 44k sample rate with 64 buffer size is not usable due to pops and cracks. The surfacebook manages that with an external audio interface. So I suspect the cause is either the usb audio device in the piano and/or there is no ASIO drivers for Windows. It might do better with more powerful devices and different OSes.
Anyhow the latency is not the reason I am not using that setup. I also need to turn off the "Local Control" to turn off the internal sound. And that is annoying. So I still have an external audio interface which is also connected to the hub. One usb cable (to the laptop) to rule them all 🙂
