Sharing front speakers between HT system and listening system.

There are preamp's that support Home Theater Bypass. Some even allow you to use the same amplifiers and subwoofers between your Home Theater AVR and your stereo preamp, in addition to the front left and front right mains and the amplifiers that power them.

I have an Anthem STR preamp that supports this and share the same FL, FR, pair of subwoofers and external amplifiers with an AVR when I watch TV.

https://audiophile.no/en/articles-tests-reviews/item/426-amplifiers-with-processor-input

There are other ways to accomplish this like switches and tape loops but HTB makes it seamless, automatic, and easy.

I should have added I use the HT system daily - it is more or less my main TV even though it is a projector. As such, I don't want to put those kind of hours on the tubes. I'll put up with the inconvenience of switching the cables before taking the Shanling out of the system... as such I don't think the HT Bypass does what I am looking for either. I could run a second set of speaker cables to the maggies and plug/un-plug there as it is a bit more convenient than the back of the power amplifiers. Was hoping someone had good success with a simple passive switchbox that didn't hurt the signal to any noticeable extent. I may experiment as switches and switchboxes are reasonably inexpensive.

You need a two channel preamp or integrated with a home theatre bypass option, along with a home theatre AVR that can output the front channels independently.

This will allow you separate the two systems with as little as two shared cables.

Here is a list of the preamps with a HT bypass capability.

https://www.audiophile.no/en/articles-tests-reviews/item/426-amplifiers-with-processor-input

@audiotroy 

@Tony1954

+1

I use this all the time for comparisons and trouble shooting.  Will do what u need.

https://fosiaudio.com/products/fosi-audio-lc30-amplifier-speaker-switcher