Here's a test to clarify this. Plug your CD player into a non-direct input first. Play a CD track that is dynamically/compressed (most pop music will do, e.g., Sugar Ray's version of "Abracadabra" has only 3 dB of dynamic range) and set the volume control to a slightly loud setting and leave it there. Change the CD connection to "direct" input (turn amp and preamp off before doing this, of course, and turn them back on after switching inputs), and play the same track without changing the volume control setting. If the line stage is not used on the direct input, the sound level should drop substantially (by the gain factor of your line stage). If the line stage is active on the direct input, there should be no change in level.