I have Odyssey Khartago mono amps and it is recommended to leave them on. Is it wise to leave the tube pre-amp on as well? There is a noticable thump from the speakers at pre-amp turn on. Also, the amp appears to cycle off/on when I turn on the pre-amp? The amp clicks, like when you are first tuning it on, when you turn on the pre when the amp is already on.