Konstantin,
Correct, if you use an Integrated amp with no HT bypass/Processor loop, you will need to set the volume of the integrated to the "calibrated" level each time you want to use HT. Not as bad as it sounds. Simply set the volume to a pre-described level before doing the initial calibration of the HT setup. For instance, set the volume to top, dead center or 50%, whatever. Then, when using HT, just set the integrated volume to that position.
Enjoy,
TIC