[QUOTE=CDan;2031424]TMPGEnc-Author3 does not re-encode 5:1 audio unless you apply filters or make other changes that result in video or audio re-encoding. In short, 5:1 in means 5:1 out. I haven’t tried it with Express4, but it may be the same situation.[/QUOTE]
Like I said, I do not know Author, but Express4 (I use it) will do that without any filters or change in setting. I do have latest update and do not see any changes in audio.
The confirmation came from software company. They do not have licence for 5.1, because it will increase software price too much - their words.