Preamplifier sound Quality impact in home theatre bypass

I have been doing it for years, and haven’t had anything call attention to it. I watch a few concert videos in 5.1 and find the music to sound just as good as when I played the same discs on my old Ayer C5xe that played DVD. 

I consider HT a step or 2 below 2 channel and wouldn't worry about a pass thru on your preamp,  all that should be in the signal path is some wire and a selector switch.  Assuming you chose a preamp with good switches, it shouldn't affect HT.

A better solution, that I use, is to have an amp built with 2 inputs so HT pre-out goes directly to the amp.

Jerry

I have a Mc class D bypassing into Mc AB and definitely have not experienced any sound degradation at all.  Granted I have good cabling throughout my entire gear + on the sub.   

It depends on the tube pre and the path the signal is taking for HT Bypass. 

In many of the designs I've seen, the HT Bypass is the equivalent of putting an RCA female to female adapter between two RCA pairs. Wouldn't bother me unless you noticed a change running with and without. 

McIntosh Integrated Amps and Preamps have a really slick pass through.  I set my Dad's MA8950 with an Anthem MRX 540 and it is seamless integration 

The MRX's trigger out goes to Mac's control trigger input and when you turn the MRX on it puts the Mac in Pass-through.  It's just using the MA8950 amps,  with the MRX doing volume and powering the centers and rears.