I read some informations about Dolby Surround, Dolby Pro Logic and Dolby Pro Logic II.
So, for Dolby Surround (1982) : this is the first technology of Dolby for stimulate a surround system. It's a 3 channels (left, right and surround in mono : the two rear speakers produce the same sound) system. The stereo source has to be
encoded in surround (along with a matrix). But there is a limitation of frequency for the surround : it is limited to 7kHz (but what means this limitation ? less treble or less bass ?).
For DPL (1987) : this is an evolution of Dolby Surround. It supports now 4 channels (left, center, right, and surround still in mono.) but has always the limitation of 7kHz and always needs a stereo source
encoded in surround (along with a matrix). If you have a subwoofer, it will produce bass sound but there is no attributed channel.
For DPLII (2000) : this is the biggest evolution : it supports 6 channels (right, left, center, right surround, left surround and subwoofer). The surround speakers are in stereo and have no longer the limitation of 7kHz. The subwoofer have his channel.
And the last evolution of the DPLII is that it can now stimulate a 5.1 system from all stereo sources (not only these encoded in surround).
It has two mode : movie, for the stereo sources
encoded with surround and music for the only stereo sources.
There is a last evolution (Dolby Pro Logic IIx) which is more complicated.
Every evolution has a better matrix technology than the previous one.
So, Wii games are
encoded (can we really say encoded?) with Surround so the decoders with Dolby Surround, DP and DPII are compatible.
I made this post to help some people who wondered about theses technology, like me some hours ago
Thank you for your help, if you have more informations, tell it
And sorry for all the mistakes I made !
EDIT : as Vinny said, it is better to say that there is a matrix added to the two stereo channels instead of saying that the source is encoded.