No ports of any kind when near the walls and piano.
I have a piano on my side wall, but surprisingly do not hear any complimentary vibrations when I use my test cd, playing/stopping 1/3 octave test tones.
My friend has a 'seismo' app and walks around my room finding this and that. Top of my dining room table 'adds' something, but never noticeable or detrimental and I keep a heavy table cloth on top anyway.
My toe-in is flexible, find the best for single chair, and adjust toe-in when two listeners to maintain decent awareness of center and other side,
Tilt them back to avoid parallel reflections off the ceiling/floor, and 'mess up' the side/rear wall reflections (tweeters aimed at seated ear level).