Loxone Music Server line-in audio delay

[smartbusinesstools.be]

The problem:

When playing audio via a Line-in of the Loxone Music server to a zone, there is a fixed 3 seconds delay. This impedes some practical use cases:

• you can not play audio along with video (TV, YouTube, persentations, etc) because the audio will be 3 seconds out of sync
• controlling the external audio source is difficult because you don't get immediate audible feedback, e.g. when turning up the volume in the external user interface, the volume only starts to increase after 3 seconds, making you turn up the volume to high
• mixing music during a home party (via an external mixer) is not possible

In the Loxone App, you can set a parameter Audio Delay under Settings for each zone. However, when selecting a Line-in as the input for the zone, the delay is fixed at 3 seconds, independent from the value of that parameter. This is documented at the bottom of the documentation in German 

HINWEIS ZUR WIEDERGABE VON MUSIK ÜBER DEN LINEIN EINGANG:

Der aufzunehmende Ton wird nicht in Echtzeit übertragen. Es können Verzögerungen von abspielender Quelle bis zur Wiedergabe über den Music Server von bis zu 3 Sekunden entstehen.

but is missing from the documentation in English 

I checked with Loxone and they don't have a solution for this problem (actually they are saying it's not a problem because it's not intended for that use), so I'll need to come up with my own.

Some possible routes might be:

1. use another device with a line input that can digitize and stream audio fast to the Loxone Music Server. In the App, I should then be able to select that stream instead of the local Line-in.
   
2. use a mixer to add the audio signal to the zone output of the amplifier. It won't be controllable from the Loxone app, unless I can find a mixer that you can control, and how then would you select that source from the Music interface in the App?
3. not mixing but switching between signals via the Miniserver's relay contacts. The same problems as in 2 remain, plus there will likely be a loud click through the speakers when switching, which might damage the amp or speakers.

I think 1. would be the simplest solution and possibly inexpensive if it can be done with a Raspberry Pi. Anyone knows where I can find the software?

For playing audio along with video and for mixing, I think the delay should be <20ms. For feedback to the user interface only ,we are fine with <200ms.

Any other ideas for a workaround?

[smartbusinesstools.be]

Or would it be possible to change the delay via the Music Server's webservice API? How?