This may not be a that typical configuration, but I use Pristine Space as digital XO and for digital room correction. To make usage easier, the engine is always running, even if no music is played, no DVD watched etc.
Brutefir, a convolution engine for Linux, has a nice feature to save power under such conditions; here is the full description taken from their web page:
The powersave feature if activated, will monitor the inputs, and if an input channel provides zero samples, the associated filters will not do any processing, since with zero on the input, BruteFIR knows in advance that there will be zero on the output. BruteFIR will continue run as normal, and filters with non-zero inputs will continue to to process normally. As soon as there is non-zero input on a suspended filter, it starts processing again. This powersave feature is transparent, there will be no convolution errors if it is activated. The reason for having it optional is that one may want to make performance tests, without the need to feed a meaningful signal to BruteFIR.
If analog inputs are used, the input will never be exactly zero, and thus the powersave feature will not be triggered. However, if a value is specified instead of the boolean (for example powersave: -80;), that value is interpreted as the lowest level in dB the input signal can be, before BruteFIR will consider the input as zero, and trigger powersave. Thus, a noise floor can be specified, and then powersave can work together with analog inputs.
Any chance to see this feature also realised in Pristine Space?