Readynas Duo V1 / Twonky

I have a problem with transcoding Flac to MP3 when I don’t want it.
My configuration is
- Simple Audio Roomplayer
- ReadynasDuo V1 with Twonky 6.0.38
(Twonky is supported by Simple Audio)
- PC
- iPhone

My music files are stored on the Readynas as Flac.

1. When I select a Flac file from Simple Audios Desk Top Client on the PC
the Roomplayer plays OK.
QUrl( http://192.168.0.64:9000/disk/NON-DLNA/O0$1$8I183960320.flac )
which is right.

2. But when I close the Desk Top Client and control the Roomplayer from
Simple Audios iPhone app the Flac file fails
The reason seems to be an unwanted transcoding from Flac to MP3.
QUrl( "http://192.168.0.64:9000/cgi-bin/Xflac-mp3.desc/NMP3/DLNA-PNMP3-OP01-CI1-
FLAGS01700000/O0$1$8I183960320.mp3" )
which is wrong.

Selecting an MP3 file in the same way works fine.

In both cases I select the same track.
Transcoding in Twonky configuration file is MP3=0 (disabled) but it seems
like Twonky transcodes the Flac file to MP3 as soon as I use the iPhone to
control the music.

Can anyone give me a clue?

Per-Arne from Sweden