TheNinais a hybrid analog-digital synthesizer, and that hybrid aspect runs through the entire design.
This is the holy grail for musicians, who almost universally prefer hands-on control.
Knobs let you adjust by feel without having to line up a mouse pointer with an on-screen circle.

Melbourne Instruments
But knobs also offer valuable visual feedback.
you’re able to tell at a glance how they are set.
When knobs are used to control software, things can get out of sync.

Melbourne Instruments
If you make an adjustment on the screen, the knob no longer shows the current setting.
There are ways around this.
Another option is to have a ring of LEDs around an endlessly-rotating knob to show its state.
And another, used by the Nina is to put motors in the knobs.
Fine Motor Control
Nina’s knobs not only look cool but can perform some extremely useful jobs.
One is something that eludes most analog synths: presets.
With Nina, when you load a preset, the knobs immediately shift to reflect the parameters.
“In addition, knobs that always show their state can be beneficial for users who are visually impaired.
But those motors aren’t all good.
One downside is that they push up the price.
The Nina goes for $3,599.
And the motors may be more likely to fail than non-moving LEDs.