Line level switch ahead of the tube amp so you use if for home theater too, speaker level switch down between the two, and in the later case care to make sure you don't feed the amp a signal when the speakers (you get more voltage swing when it's unloaded and can cause arcing in the tube or output transformer) which could be as simple as turning off either CD or amp.
Xantech and Niles sell switches which can be controlled by IR or the 12V trigger signal on home theater equipment.
Xantech and Niles sell switches which can be controlled by IR or the 12V trigger signal on home theater equipment.