Most of us don't need discrete, but it's an option. We weren't really discussing adding height to a matrix, but I'm sure it's a possibility. As for using the same mix for both matrixed and discrete, I've encoded from discrete sources, using Involve's Evaluation Encoder module, and the results are quite excellent. A-B comparison of the two shows it's difficult to tell the difference between the original discrete, and the encoded signal. The module isn't at all expensive, and it works most effectively. They also offer a professional model, too, perfect for recording studios. Check their website, Involveaudio.com.
