I have two Source Technologies HVS 10/500 subwoofers. They have built in Class D amps. I only get to listen to my stereo once or twice a week. My question is should I leave the subs turned on all the time. They go into a standby mode if there's no signal going to them after a while. Have read where its OK to leave Class D amps on all the time. I have a tube preamp so right now I turn them and the preamp on about two hours before I'm ready to listen. Thanks for any feedback.