Great sounding close to back wall speakers.

If you're looking used, the Linn Isobariks were designed to placed within a couple inches of the wall. In good condition, a fine sounding loudspeaker.

-R.

The materials and kind of wall construction will be crucial to making this work in my experience, regardless of speaker. You need to avoid unwanted vibrations from the wall itself that will muddy or enervate the sound. A modest wall treatment might be the best investment you can make. I've had some speakers as close as 12" with good soundstaging and bass balance. I'm no acoustic expert, but if you are interested in this issue, let me know and I can share my experience treating the wall.

It's hard to guess what will work in a specific location, but certainly speakers designed to work close to the wall should be the focus of your search.

In the relatively high efficiency group, I've heard and liked the sound of Audionote speakers. The cheaper models are very good for the money, the more expensive models are better, but the declining marginal return is steep with this line.

In the less efficient group, I like the Gradient Revolution. I've only heard it at two CES, but they sounded great in rooms/locations that had to be hard to work with.

Having a front or rear port location doesn't matter once you get more than a few inches out from the wall.

Within the ports operating range the sound waves are _very_ long (28 feet at 40Hz), wrap arround the speaker like it wasn't there, and the speaker isn't at all directional.

Except for dipoles, horns, and cardioids all speakers are going to have a substantial (like 5dB) bass boost below 70Hz when placed within 2' of the wall.

I find that objectionable; if you do too you'll want either a speaker specifically _designed_ for on or in-wall placement or a parametric equalizer with a shelving high-pass filter.

Smaller Dunlavy (SC-IV or smaller) or Duntech (Princess or smaller) speakers will work OK as you mention, you'll lose a little depth and might get a bit more bass than otherwise specified in the measurements but otherwise you can be OK. The best close to wall speakers I have ever heard are the Snell Type A-IIIs, designed to be placed up against the wall and terrific speakers. I think there's a used pair up for sale on the 'gon now. Particularly good with classical music, and good bass extension. Only problem is that they're no longer in production, don't know about how well they can be serviced/repaired.