[scomment]

> Why would you want to cast mixer to something else?

Did you ever heard about interfaces? You can have a IMixer interface, a Mixer baseclass and some concrete mixer classes depending on your task. Like null-mixer for mocking, software mixer for legacy computers, hardware mixer with GPU support, etc. Use your imagination, Luke!

[chipsy]

Or you could just have data. The behavior of mixing is not going to change because of those things.