I use a Supratek Sauvignon tube pre-amp with my Spectron and have no problems shutting down the pre with the amp on.
If you have a mute switch or even better a HT bypass switch use that before shutting the pre. You should have no problems, always lower your volume firsthand.
If you have a mute switch or even better a HT bypass switch use that before shutting the pre. You should have no problems, always lower your volume firsthand.