Thanks for your comment.
It's clear, the Bose Soundtouch is only a 2.1 device.
All I want is to play a movie with DTS-HD 7.1 and hear the sound on the Bose as 2.1. The Bose Soundtouch
accepts a DTS 5.1 signal on its input and plays it as 2.1
Therefore Kodi has to downmix the DTS-HD 7.1, which is contained in the movie, to DTS 5.1.
This works only if the H8 is connected via SPDIF , but not via HDMI to the Bose Soundtouch.
When connected via HDMI the Kodi shows the audiotrack as DTS-HD 7.1 (the original, as contained in the movie),
but the Bose Soundtouch cannot play this and stays mute (no sound at all).
When connected via S/PDIF the Kodi shows the audiotrack as DTS 5.1 (downmixed from DTS-HD 7.1) and
the Bose Soundtouch recognizes the audio and plays it as 2.1. So it should be.
Playing the same movie with Himedia Player works with SPDIF and HDMI.
Himedia Player shows the audiotrack in both cases (HDMI and S/PDIF) as DTS 5.1.
I think the downmix in Kodi from DTS-HD 7.1 to DTS 5.1 is not working, when the
H8 is connected via HDMI, but works with S/PDIF.
Kodi configuration is done as shown in http://www.futeko.com/newforum/index.php?topic=337.msg2299#msg2299 (second setting)
Any ideas?