The HDCD component is only for decoding the HDCD data in software. If you want to play it directly to a hardware decoder, you need to remove the HDCD component.
Without the component the Stream will be played as it would be played on a regular CD player (i.e. the regular 44110Hz/16 bit PCM). If you output this bit-exactly to an external interface with a built-in HDCD decoder, it can then decode the HDCD data of the stream. So, in short, if you have an external HDCD decoder, don't use the plugin, since the plugin is a HDCD decoder itself.