If you want media player that plays HD audio, currently only the higher priced ones can do that, e.g the Dvico 6500A, HDX BD1, HDMAX-BD-200C (all above RM1K). You will also need an AVR with HDMI input which also supports HD audio. (Note * Just having HDMI is not enough, it must also SUPPORT HD Audio, whether Bitstream or LPCM).

Those movie files with HD Audio (TrueHD ot DTS-MA)  are normally files with  .M2TS extension.

Those with .MKV extension normally only contain downconverted Regular Dolby/DTS 5.1.

(Note:- Although the cheaper Media players can play .m2ts files, the audio will not be real HD Audio, only downgraded 5.1 sound or sometimes even no sound)

They Can contain but they are not the norm yet, that's why I use the word "Normally".

WDTV Live may play TrueHD but what about DTS-MA. Partial function don't count as the real thing  because lots of m2ts are using DTS-MA nowadays 

All I see are files with just regular AC3 and DTS 

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Added on March 17, 2010, 12:15 am
Like I said TS looking for info on Current Media players in market, not something that relates to future  . If he buys the Asus O!Play thinking it can play MKVs with HD Audio in future then you better answer to him in future