Are planar speakers less prone to room interaction

Dipoles interact with the room differently from monopoles, and have different setup requirements for good performance. Briefly, dipole bass is smoother in-room than monopole bass, but you don't want the reflected backwave energy arriving at the listening position too soon. I suggest about 5 feet between the speakers and the wall behind them.

Also, with a hybrid electrostat, the line-source-approximating panel will have different radiation characteristics than the point-source-approximating woofer. The sound pressure level will literally fall off more rapidly with distance from the woofer than from the panel (anechoically, 6 dB falloff per doubling of distance for a point source vs 3 dB per doubling of distance for a line source). In a long room like you have with hybrid electrostats at one end, the relative balance between woofer and panel will change by about 4 dB as you go from a fairly close listening position back to the far end of the room.

I used to have a room somewhat similar to yours (mine was 31 feet long by 13 feet wide by 9 feet tall), and large fullrange electrostats worked well in it. That 4 dB variation with distance is what I measured in that room with a hybrid electrostat. I think that big Maggies would be a better choice for your room than a hybrid electrostat.

In my experience, loudspeakers with fairly uniform, preferably not-too-wide radiation patterns are a good choice for problematic rooms. Some dipoles fit this description, as do some monopoles.

Duke
dealer/manufacturer

I aggree with all of what Jwpstayman said, with exception of the M-L's having a "much narrower dispersion pattern." I'm using Maggies(MMg's) in my bedroom system and having very little in the way of secondary reflections from the side walls(and they are close) Excellent freq. response curve, imaging and sound stage(especially for such a small room). I only treated the wall behind my listening position(a bean-bag on the bed) with Auralex to prevent standing waves. I wouldn't hesitate to go with either Magnepan or Martin-Logan in your situation, as they are both excellent system manufacturers, and given the power, will generate realistic SPLs(at least their larger systems will). If you should need further room treatment, check these out: (http://www.asc-hifi.com/picture-panel.htm) Let your wife pick the pictures(good for the relationship). Peruse the rest of the site for some really good pointers on room acoustics. Happy listening!

Thanks all for your fantastic and detailed responses.

Jwpstayman: It's more the asymmetry that is disturbing to the ear. Immediately to the left of the listener's location you have the windows, whereas to the right you have the empty space where the room doglegs into the kitchen. That leads to a really annoying image instability - as a singer goes up and down their range they will move from side to side. I'm assuming this problem is caused by the windows, though there's other things that could be a factor (the exposed ductwork on the left and not on the right; the chaise of the leather couch). I'll definitely look into the Marigo dots - hopefully they will mitigate the problem somewhat (the double cell blinds on the windows now don't do much).

Duke: That's incredible detail, thanks. It never would have occurred to me how quickly the drop-off in perceived volume would differ as you moved around the large room. I'm not sure I can afford a full-range electrostat but the larger Maggies can be found around $1000 which seems like a feasible replacement for my PSB Image T45's.

Hudsonhawk, Maggies and Martin Logans are definitely competitors. If you read a lot of online comments, you'll find that people pretty much agree on what the tonal balance of Maggies is whether they like them or not, but then you'll find a diversity of opinion on what the tonal balance of Martin Logans is. I think the reason for this can be traced back to the Martin Logans radiating as a point source at low frequencies and as a line source at midrange and high frequencies.

Used Maggie 1.6's should work well in your room, assuming you have a fairly powerful amplifier.

Duke

save your pennies. martin logan is producing a full range electrostat, the clx. yes it will exceed your budget, significantly. it will not have the disadvantages of a hybrid electrostatic speaker. it will, unfortunately, set you back around $8000.