Besides saying 5' off a wall tehre is a formula out there to help avoid standing waves and all sort of issues that place your speakers based on room size. The speaker in general should be measured from the middle of the cone not the enclosure.
To tell you a story though I had a really good guy came in and tune my room. He started by the book placement, then tewwkwd to his sound meter and in the end did slight tweeks based on ear.
To tell you a story though I had a really good guy came in and tune my room. He started by the book placement, then tewwkwd to his sound meter and in the end did slight tweeks based on ear.