The Samsung HW-C450 soundbar can be compatible with the Dyon Smart 43 XT TV, but there are a few things to consider:

- The Dyon Smart 43 XT has multiple connections, including 3x HDMI, 1x VGA, and 1x Optical-Out.
- The Samsung HW-C450 soundbar has an optical-in connection, which means that it can be connected via the TV's optical output.

It is therefore possible to connect the soundbar via the TV's optical output, which enables a compatible and functioning connection. However, it is advisable to check the specific connections and settings of both devices to ensure that everything is configured correctly.