I would leave the CJ's off if your not listening. While its true that that intitial electrical current that runs throught the circuit when an electrical device is turned on is responsible for shortening circuit life, in the case of tubes thier life expectancy (at least for listening to music) is such that the wear and tear from on/off modes isn't going to manifest itself into any audible damage within those few thousand hours that the tube is actually good for.
