I checked this and as it is mentioned in manual, with 3 position switch you have:
-All sounds off
-Vario sound on
-speech announcements on
So there is no option to have both vario sound and speech announcements on at the same time.
This is not practical in thermal flying because then it is needed to hear vario sound and be able to check altitude with speech announcement without using any switches for this.
So the only way for this is to use flight phases as there it is possible to choose which audio is on in every phase. (= choose the mode where speech announcements and vario sound are on in one of the phases)
Ps. 1 The "all sounds on"- mode is done in that way in SX1 so it is an alternating function (="im Wechsel"). I don't understand what is the benefit of this, why in this mode both vario sound and speech announcements can't be simply on all the time. It would be good to know why this mode must work as alternating ?
Ps 2. I can understand German, so comments in German are OK.
Jussi