So I wonder, if one can really convert a session cleanly to another sample rate without exporting every single track and importing those tracks to a very new session…
I made a script that re-samples all .wav files in a given directory to what the SR you want. That’s how I did when I changed from 48k to 96k many months ago. Of course you have to check that the session is set to the right SR afterward. I don’t have it here at work but I think it is somewhere in linuxmusicians.com or the hydrogen forum, don’t remember now.
I did the very same using sox - the files are sane(in MHW at least). Starting the session with jack running at 48KHz gives a message like this:
“Session was created at 96KHz - start anyway?”
then it starts without any more messages.
But alas: the peakfiles are messed up completely and I have randomly appearing loud sinus-sounds (like very nasty mic-feedbacks).
So converting the sounds is not the real issue - reanimating the session itself is.
Update: tried this but to no avail
after deleting the peakfiles ardour rebuilt them but they did not show the real audioevents. Some parts of the song are played nearly correctly others are not played at all or mixed up completely. The most annoying sideffect is a loud whisteling sinus-sound around 400KHz that does NOT stop if transport is stopped.
The unconverted session works perfectly at 96KHz so do new sessions created at 48KHz. The files converted by sox can be opened and played without any trouble with mhw.
Ah - thats an interesting trick - will try it asap
thanks 
You can always delete all the peakfiles - Ardour will rebuild them as needed. It will take a while on a session of any real size though, so be prepared to wait for a bit when first (re)starting the session.