SLL: You get to pick what frequency the HPF rolls off at. (40, 60, 80.....)

Llamas: The difference is subtle, but IMO important. For instance I could have a Pioneer 47ai connected to the preamp and then begin creating a set of tasks like this:

DVD-Video: Route component video in 1 to video out, Route optical input 3 to all digital outputs and bitstream decoder and then out the audio outputs, using first of the following modes that will work on the bitstream. Set volume to current setting or -40, whichever is less. Use the following level trim values [][][]. ......

DVD-Audio: Route component video in 1 to video out, Route optical input 3 to all digital outputs and the 8 channel audio input to the audio outputs via the analog BM and gain section.

CD-Music: Blah Blah Blah Blah Blah.....

It's pretty similar to what a remote does, but rather than issue a ton of commands from a 3rd party device put the brains to do it in the pre/pro. You've already paid for a CPU, memory, interface - use it.