Yes.

When you connect to the UD951B decoder and the sound of the TV or TV box is set to source code output (raw data / passthrough / bitstream), By now the audio signal will be decoded and output by the H951BT decoder, instead of audio decoding by TV or TV box. Therefore, the original TV ( or remote control ) / TV box ( or remote control ) is going to can no longer control the volume.

All is almost the case when you use an external / stand-alone decoder, Which you can no longer control the volume through the original TV ( or remote control ) / TV box ( or remote control ).

If you really want to control the volume by the original TV ( or remote control ) / TV box ( or remote control ), you can set the TV (or TV box) sound to the" PCM " output, so that the volume can still be controlled by the original TV ( or remote control ) / TV box ( or remote control ).

But the " PCM " output is only virtual 5.1.