I have a Sony Bravia, model # KDL-48R510C. It has 2 HDMI ports. Port 1 is (ARC). The Roku Express must go in port 1. If I connect the home theater system to port 2, the TV recognizes it but does not play sound. The model number for the HTS is DAV-TZ140. What do I need to do to be able to use the sound system with my Roku?
… which means you have a problem with your HDMI port 2.
Does your HTS have any audio inputs? The specs say nothing about that. If there's an input, and your Roku does not have dedicated audio output, you might try HDMI Audio extractor device between the TV and the Roku, with output audio going into the HTS.
Port 2 works fine with other devices. When I plug the Roku into port 2 it gives an HDCP error. It seems like both devices need to be plugged into the ARC . My HTS has only composite inputs ( and outputs) and 1 HDMI output only. The HTS was a Mother's Day gift from my son a couple years ago, otherwise I would have given up already.