Streaming high quality videos without loss of quality? Is there any software on PC/Mac which just 'serves' the files of system to iPad (instead of converting them on the fly) and any app which is able to play such content?

I tried Plex, though it streams most of the videos, but quality isn't great. And I have even enabled Direct Play  which as per description :


  Allows the player to play compatible media without any conversion. In
  most browsers, direct play supports MP4 videos with h264 video and AAC
  audio. Videos with subtitles cannot be played directly.


However the quality isn't same when I compare the same file in AvPlayerHD. I tried a 12GB MKV 1080p video, I felt quality was far superior in AvPlayerHD as compared to streaming. 

Basically I don't want to convert and use CPU of my PC, when my iPad is perfectly capable of playing such quality content, why convert at all? 

So is there any app which does that? And also I heard Air Video does this, but I couldn't find any info.
I use Air Video HD (US$3) and the free server for OS X.