Can Electronics Affect Speaker Placement?

When I started out in audio five years ago, I experimented with speaker placement until I had a pretty good soundstage. A year ago I placed some bookcases along the walls to the right and behind the speakers, so I relocated the speakers to adjust to their new room boundaries. Within a four month span earlier this year, I replaced my amp, preamp and cd player, with noticeable improvement In the sound. I am also about fo replace my speaker cables. Does it make any sense to tinker further with speaker placement because of the new electronics and cables? I know that the dispersion pattern of the speakers and the interaction of particular sound wave frequencies with the room boundaries remain the same, but wonder if the stronger lower mid-range and upper base frequencies I now enjoy might be reason to further adjust the speakers’ placement. Of course, I could always experiment and find out, but any improvement might be due simply to improving the speaker placement regardless of the changes caused by the other equipment. Thanks for any responses.