The MP 2016S replaces the MP 2016a with a new internal universal power supply (100-240 VAC). All other features are identical. The XP 2016S gets the same new internal supply.

All previous versions are compatible with the new 'a' versions.

An XP 2016S works with an MP 2016 or MP 2016a, and an MP 2016S works with an XP 2016 or XP 2016a.

It is not possible to change parts to make an older unit to a new 'S' version.

These mixers use the highest quality Alps potentiometers.

---