Good point, I should clarify ...
The integrated will be used as-is most of the time. The system is in a dedicated "media" room for stereo listening and occasional movie watching. I don’t care too much for HT so movies will go through this same 2ch setup.
I enjoy DIY audio and have built a few tube amps, some 300B SET, EL84 push-pull, an EL34 push-pull is in progress.
I’d like to be able to easily integrate one of these power amps into the system for casual listening.
The nice thing about using the pre-outs of the integrated for this is that all of the sources (DAC, tuner, turntable) will already be connected and the remote control and various preamp functionalities (volume control, source switiching, balance) can be used.
Given that the integrated has a speaker off switch, I could easily go between solid state (Speaker switch on A, tube amp off), and Tube amp (Speaker switch to off, tube amp on)