Tube preamps with HT bypass


Anyone know if any models that can engage the HT bypass with the power off or at least without the tubes burning?  Thought I read about one or two a loooong time ago that were able to do this.  Thanks!
soix
I know that the Backert Labs preamps have a HT Bypass that works with the preamp turned off.
I believe my VAC Renaissance Mk3 cinema pass through worked when the unit was not powered on.
Audio Research does not work with the preamp off. Which can be good or bad depending on how you look at it.
My Bryston 2.5 SST2 amp has RCA and Balanced outputs. The RCA's go to my Luxman CL38U SE. The balanced to my Krell Showcase preamp. I just flip the switch on the amp. No need for HT pass through. Lets you buy any tube preamp you want. The Luxman doesn't have HT pass through.