[rcrh]

This is a bit off topic from Kodi but I figure a lot of people here may have an option.
In the absence of surround sound is there any advantage to using AC3 (or DTS for that matter)? I've got some older TV shows & movies that I want to archive and I'm wondering if there's any reason to not reencode the audio to AAC. Some of this content is not just in stereo but in mono.
Any thoughts would be appreciated.

[Prof Yaffle]

This is a bit off topic from Kodi

Yes, it is, so I'll move it there for you

any reason to not reencode the audio to AAC

My immediate response is "why?", as you'll always lose some quality by re-encoding to a lossy format, and I'm not sure what you'd gain beyond perhaps a slight reduction in physical file size. The only other reason I could think of is if you're limited in what your playback client (or AVR) supports, but that's a reason to get a better client and not permanently throw away some information IMO.