The system is powered up using a remote sensor connected to the power-save device, at which point the Shuttle starts booting immediately, followed by the TV once I push the power button on the remote a second time.
As a result when the Shuttle first boots it sees nothing connected to the HDMI output and consequently disables it until X starts. Not a huge problem, but it means I can't see it booting and hence won't see any issues flagged during the boot process.
Is there any way of forcing it to enable the HDMI output any earlier, e.g. with a kernel parameter in the pxelinux config file?