Kursula.... Thank you for your kind words!You are the first person to ever call me a genius. Obviously, mathematics wasn't one of your stronger subjects.A couple of dozen preamps? Would that be 24?, where did you hear that!I have owned 10 or so "personal" preamps over a 35 year period. I have worked in the recording industry as well as the professional sound business for many years.Also ran a DJ company with 10 systems out in the feild and used a boatload of preamps,solid state as well as vacuum tubed equipment.Have serviced sound equipment for 35 years.Still use and maintain a vacuum tubed Studer pro tape recorder.To answer your pointed and rather dubious questions: I have 5 vacuum tubed preamps currently in use.The much modified Dyna pas 2[12ax7's] that I built from a kit back in 1967 which is still being used in my office and is very rarely turned off.My ARC-sp-10 mk2 in my home system gets powered up only when in use, as it is rather hard on tubes[ecc88's].As Jax2 correctly pointed out,some of the current preamp's on the market can eat tubes rather quickly ,most of them employ the 6dj8/ecc88 family of tubes. The supratek and MFA preamps in my studio are powered up at 8 o'clock every morning and turned off only when I leave. The home built preamp [tubed rectified 6sn7's]in my kitchen is on about 16 hours a day.. every day. The gentleman[meech] is new to tube equipment and asked a specific question. The point I was trying to make... was to run in a "new" preamp with new tubes.I am not suggesting every one here leave their equipment on. ALL preamps,solid state or vacuum tubed will sound far better an hour after they are powered up as Jax2 alluded to ... particulary vacuum tubed preamps.Most preamps designed around the 12a?7 family of triode tubes are generally, very conservative on tubes.The Dared preamp[12at7] falls into that category.However...The transformer, as well as coupling caps in any brand new equipment need to be run in with a modulated signal and will not come into their own for many hours. While my supratek syrah sounded very good right out of the box,It improved daily and did't reach its full potential for more than 200 hours of use with a modulated signal running it. Running a cd player[on repeat] through a new preamp is a great a way to run it in.You don't even have to turn on your amplifier or listen to it for that matter. Kursula...If you choose to wait an hour or so to get the best from your rig, that is certainly your perogative! Some of us here would choose not to do so. PS: Just curious Kursula, Do you actually have a vacuum tubed preamp?