You might come into several issues.
USB is more complex and has much/more protocol overhead and thus needs more CPU power.
So more CPU power would be required on the keyboard itself and also on this "next generation" recording interface.
By this you add two times latency for the processing of this data and maybe also by the USB protocol itself.
Recording Interfaces have usually limited FPGA resources, so this all would need to be handeled additionally per connected USB keyboard device. FPGAs are expensive. The usual companies producing the usual keyboards would not take FPGAs and implement USB therein. They would buy simply USB controllers from the market from which we know that they have often compatibility problems.
More technical aspects in terms of data transport: How do you keep data in sync, if you need to transfer audio and control data (like MIDI).
And all these efforts sum up with each additional USB port that you would require for such an interface.
How do you design this ?
One USB port with a HUB for many devices ? Or dedicated USB controller per device ? (-> costs, complexity)
This is from resource / price perspective much of an overhead.
Then you would additionally get all the incompatibility problems by USB controllers not 100% applying to the standard that we have now luckily only between PC and recording interfaces additionally between the recording interface and all the devices that you want to connect to the recording interface via USB ?
On top you get with USB additional problems, as cable lengths are limited. For a standard USB2 cable 5m.
With a digital cable you can achive longer distances, optical SPDIF up to 15 or even 20m.
This all makes for me absolutely no sense from whatever angle you look at it. Cost, performance, latency, stability, compatibility, ...
You should maybe better ask for
- keybords with digital output like SPDIF or AES. For this you can take standard solutions where the transport of digital data is much easier to process, with less latency and where standards are already there
- and if we then really have more digital devices for more digital ports on recording interfaces. But this makes only sense if the amount of devices to be connected digitally would really increase.
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