If your system sounds a bit tired and lackluster, it's either you or the tubes have started to go bad. Sometimes older tubes develop noise problems as well (sputtering and whistles, etc.).
How does sound change when tubes start to fail?
Maybe a silly question, but I'm wondering how I can tell when the output tubes in my Fisher 400 reciever start to die? When I had it refurbished the techs told me the 7868 tubes were nearing the end of their usable life. I feel like the top end is less detailed and dynamic than it had been in the past , HOWEVER, I just moved and have a new listening room with less than optimal speaker placement. Thanks