Your understanding is incorrect. dtsdecoderdll.dll (DTS/DTS-HD decoder) of TMT3/TMT5 does not downsample DTS-HD MA/HRA. If you own TMT5, then
1) Place
the custom version of checkactivate.dll in C:\\Program Files\\ArcSoft\\TotalMedia Theatre 5\\Codec for Windows 32-bit, or C:\\Program Files (x86)\\ArcSoft\\TotalMedia Theatre 5\\Codec for Windows 64-bit.
2) Register ASAudioHD.ax by regsvr32.exe (
detail). Without the custom version of checkactivate.dll, you can't register ASAudioHD.ax. ASAudioHD.ax is a filter, called "ArcSoft Audio Decoder HD", that uses various dlls to decode compressed audio formats (TrueHD, DD+, DD, DTS-HD MA/HRA, DTS). dtsdecoderdll.dll is the real DTS-HD decoder.
Now eac3to can use dtsdecoderdll.dll.
BTW LAV Audio Decoder can use dtsdecoderdll.dll directly without placing checkactivate.dll or registering ASAudioHD.ax to decode DTS-HD at video playback. Using ArcSoft Audio Decoder HD itself is another method of real-time HD audio decoding (
here).