Hi Sonicfox,
Note exactly what I said: "you can actually put them ON an open bookshelf." I did not say "in" as you stated. An "open bookshelf" is just that, one that isn't encumbered by nearby shelving above and beside the speaker.
I do not advocate burying bookshelf speakers in an entertainment center where nearby boundaries will likely degrade and color the speaker's output. See my article on "Why Wall Units Are the Enemy of Good Sound" here:
http://www.axiomaudio.com/speakers_in_wall_units.html
Regards,
