MS Audio v4.0 sounds considerably different than existing codecs, likely due to its completely new compression schema. The sound is brighter and has a much greater frequency range than other codecs, but at a loss of crispness and precision in the upper register that many find intolerably mushy and distorted, especially for "transients," sounds that occur quickly, like a hand clap or a hihat.

WinAMP and RealAudio's MP3 playback engines were both found to not perform properly in some of the tests, whereas Xing and Sonique properly played back the test MP3 files.

RealAudio was found to perform adequately, not providing spectacular results, but generally producing the most reliably listenable files.

MP3 Variable Bitrate Reduction coding (VBR), implemented by Xing, was found to produce very crisp files, although a test has as of yet to be run to see if the files are actually of higher quality than constant bitrate files at the same average rate.