The Sony soundbar does not work with this projector. Everything works perfectly with an AV reciever, plug it in and you're done.

Thanks for the tip. I have connected a Delock HDMI switch to the HDMI ARC input and plugged the Bluray player and the Sony HT-SF150 soundbar into the switch. The projector recognises the player and sends the picture, but there is no sound. When I switch to the soundbar input on the switch, it reports that the desired picture channel must be selected on the TV set. However, I cannot set anything on the projector. In the info window, the projector shows the player as the source and the soundbar as the AV system. But no audio signal reaches the Sony soundbar

If you are not using a receiver and the soundbar, the devices and the projector are connected via the receiver, you could also use an HDMI switch (possibly with remote control) to switch between the inputs of HDMI 1.