It depends on how you use your current set-up.
Speaking personally, we use the TV as a monitor. Everything we watch is via the Humax (or other connected AV equipment), either live or recorded. This way we make use of the ability to pause live TV etc and the added bonus is that we generally view only HD channels (with the odd exception).
We also have other AV equipment connected to the TV, a BluRay player and a Topfield 5810 PVR.
My sound system is connected to the TV, not the Humax. This enables any sound that is fed to the TV from ANY connected AV equipment, to be routed to the sound system.
The Television's native volume is turned to zero.
I guess I am lucky as my Philips TV has audio out RCA connectors that are synced to the picture (from whatever source), so I do not get any picture/sound sync issues.
If you connect the sound bar to your Humax, then you will only hear sound from it when you are using the Humax. If you were watching anything from another piece if AV kit, or even the TV tuner itself, then the sound bar would not be in the equation.