Thanks again for the replies. I am still confused however.
After having read Fitbrit's explanation, I tried a Blu-Ray with DTS-MA and 7.1 channels (The Adventures Of TinTin, and although I have only a 5.1 system). At first I noticed that when I right-click, while playing, and select Stream Selection, I don't see the 7.1 DTS-MA stream, only a 5.1 DTS-MA stream. When I play the same BD in TMT 5, I DO see the 7.1 stream and can select it.
While playing in MC, in Audio Path I see as Output 48kHz 24bit 6 ch and in Changes: Convert from 8 channels to 6 channels. So that would mean that I have the lossless stream ?
BUT, when I delete the dtsdecoderdll.dll from the LAV, sys32 and sysWOW64 folders and have it only in the Arcsoft codec folder, there is no change at all. The readings in Audio Path are exactly the same. This is what I don't understand. From what I understand until now, without the dtsdecoderdll.dll the DTS-MA stream cannot be decoded. Why don't I see a difference then between using this dll and not using it ?
Anyway I still wonder how I can check if I am getting the DTS-MA or only the DTS core.