Why is there a limit of 15 different instruments to be played simultaneously, with Sound / SoundNote?

Question

It seems to be impossible to play more than 15 different instruments simultaneously with the Sound[{Soundnote[...],...}] construct. Any guesses why it is so?

With up to 15 instruments it works well:

Sound[ Table[ SoundNote[ i, {i - 1, i}, i], {i, 1, 15}]]

(* I would put an image of the output here if it weren't for the "stackexchange reputation system" *)

But with 16 or more different instruments this yields no playable result.

Sound[ Table[ SoundNote[ i, {i - 1, i}, i], {i, 1, 16}]] 

Does anyone know whether there is any way to instruct the Sound function to play more than 15 instruments?

Answer 1

The answer was already given by Xerxes. It is a limitation of MIDI, which only supports 16 channels. That Mathematica really uses MIDI is described in the docs. For instance in the tutorial The Representation of Sound:

At the lowest level, all sounds in Mathematica are represented as a sequence of amplitude samples, or as a sequence of MIDI events.