Sony Bravia profile question

Just testing a variety of media to confirm what is being transcoded and what isn't (to conserve CPU on my NAS) and I found some MP4 with MP3 audio were being transcoded to AC3.

To test I amended the 2012 Bravia profile with "<Matches container="mp4" vCodec="h264" aCodec="mp3" />"

  Code:

<!-- Remux containers with h264 video + AC3/AAC audio to MPEG-TS stream without transcoding -->
         <Video targetContainer="mpegts" forceInheritance="true">
            <Matches container="mp4" vCodec="h264" aCodec="mp3" />
            <Matches container="avi" vCodec="h264" aCodec="ac3" />
            <Matches container="avi" vCodec="h264" aCodec="aac" />
            <Matches container="matroska" vCodec="h264" aCodec="ac3" />
            <Matches container="matroska" vCodec="h264" aCodec="aac" />
            <Matches container="flv" vCodec="h264" aCodec="ac3" />
            <Matches container="flv" vCodec="h264" aCodec="aac" />
         </Video>


These actually work fine on my 2011 Bravia without transcoding the audio so wondered if there was a reason MP3 was being forced to AC3 ?

Thanks

Hmmm - Messed around so much nothing plays . Best ignore this one until I work out if I really do have an issue. Sorry.