best tube preamp with bypass for HT

If you want the "Best" bypass there is only one choice, the VAC Standard preamp. When you switch it over to "Cinema" you completely bypass the preamp and the signal flows directly to the amp. The switching is so complete that you don't have to even have the preamp turned on!! I know this works because I have the VAC Standard preamp myself. That will save you tube life. It also has remote volume and mute.
my favorite preamp was the BAT VK5i until I tried the VAC. The VAC is a cross between the CJ Premeir Line & the BAT VKSE series. It has 95% of the midrange harmonics of the CJ and 95% of the transparency of the BATS, the bass is equal to the BAT (Low & tight). It also has a separate power supply which probably helps give it such low end control.

The ARC LS25 has a bypass (Processor Mode) for HT preamp applications.

Any other info on the new Bell Canto model?? Can't find it on their website.

Miked, just went to Bell Canto site. The pre-1 is listed under products. It has a "loop" input which is a bypass loop. You can download a complete user manual from their site.

The Audio Research LS 16 also has a bypass and can be found used for around $2100