Problems transcoding to Naim Uniqute

[The Pied Piper]

I am trying to use Minimstreamer to transcode to a Naim Uniqute but seem be be having no luck.
I have MinimServer and MinimStreamer (latest versions) installed on both a QNAP and raspberrypi. My plan is to ditch the QNAP and go for low power option using the Raspberrypi (Model B).
Flac does transcode successfully and shows up as Wav24. I am using Naim iphone app and have also tried Kinsky from iPhone and also from mac.
But all attempts to transcode aac (mp4) fails and just shows as AAC playing.
So I don't know whether the converter is causing a problem. QNAP uses ffmpeg and pi uses avconv. I have also tried ffmpeg on the pi but same result.
I have looked in MinimWatch log and I do have two lines that may suggest a problem:
Thread-31: runAppleScript: running script: tell me to activate
tell me to activate
17:01:16.703 Thread-31: runAppleScript: script result: null

I have tried recoding for aac using XLD which is very good but same result every time.

Any ideas? I am pretty stumped!