A tug of war drawing might be more appropriate than a dance. 
But if you draw us dancing tango, I’m not dipping (I’ve got a bad back).
We keep saying 10.6V for our Vout, but my assumption is that you are going for the full 128 MIDI notes and the voltages are obtained as a PWM.
Note 0 is a C at 0V, at 1V/octave, each semitone is 1/12V higher so the highest note 127 which is obtained by PWM as 127/128 x Vout must be 127/12V so Vout = 128/12V = 10.667V
The 270ohm resistor computed above still works to produce 10.667V for an input voltage down to about 11.3, but if the rest of the circuits draws more than 21mA, the drop of voltage through the 10ohm protection resistor might require a series resistor slightly lower than 270ohm.
This brings me to introduce another design suggestion, for the protection circuit, why not use something like this instead of the 10ohm resistors?
Where F1 and F2 are Positive Thermal Coefficient (PTC) resistors AKA resettable fuses (about $0.25 in single quantities) and D5 and D6 are Schottky diodes.
The main advantages of this circuit are:
- the series resistance of the PTC is lower than 10 ohm, so less loss
- the resettable fuses does not self destruct like the 10ohm resistors if the power supply is actually plugged in backward, they just reset themselves once the power is removed
- provides protection against some other circuit malfunctions such as short circuits, not just power supply inversions
- the Schottky diodes guaranty a reverse voltage of less than 0.5V in case of power supply inversion, protecting most ICs, which the resistors do not do
This is an excerpt of a datasheet from LittleFuse which I believe are a leader in resettable fuses.
