I have some MLP files and want to play them in any player software using DirectShow filters. I allready tried the Sonic CinePlayer HD DVD Decoder v4.3, but the sound quality is not very good with this filter. The sound is played a bit to slow. Are there any other, better DirectShow filters? I also tried the Nero Suite MPEG decoder v5.1.2.0, but this driver didn't play the MLP file.

When I play the file with the Creative Mediasource Player I get the perfect sound. But for this player I need a Creative soundcard and I want to play this file also on computers without creative soundcard. Is this possible?

Hey, this might be for you:
There is a guy named Ian Caulfield who has "been working for a while on reverse engineering the MLP audio
stream format, and writing [his] own decoder", like he says on the FFmpeg-devel mailing list. He has attached his decoder there in form of a patch to FFmpeg for review. (David already mentioned it yesterday.)

And there is already a FFmpeg build with the patch applied.
So you may be playin your MLP or TrueHD streams with free / open source software soon!..

I'm looking forward to Ian finishing off the MLP decoder for FFmpeg, but for now, Creative Mediasource Player if working with my non-creative sound card. Download it free from http://www.driversdown.com/drivers/5616.shtml (or 64-bit at http://www.driversdown.com/drivers/5621.shtml). You manually extract the setup launcher, then go to the setup file, if with vista select XP compatibility mode, run as administrator if necessary, and it will install and WORK on a non-creative sound card! Not a bad option for now.

But, I have no idea if it downconverts (I'm not connecting it to home theater at the moment anyway), and it also has some issues with runtime (thinking some tracks are way longer than they actually are, so if you jump forward in a track you may have jumped too far and it annoyingly stops).
It was clearly designed to play an MLP stream within the environment of an AUDIO_TS folder, where it's contained an AOB stream and has IFO files to guide it. But it's great that it can play back raw MLP streams with relative ease!