Acoustic Energy Aegis Ones (or the newer EVO 1s). I've used this combo and it's very nice. The Aegis Ones claim 90db, the EVO ones claim 89db... since they're almost exactly the same, I'd guess they're both really more like 89db. They're mega-inexpensive also.
I'm currently using Wave-8s in my bedroom with Meadowlark Swallows (89db again I think), and this is a great combo also.
I've also used older Bozon Acoustics A60s, again 89db.
You don't need crazy efficiency, just good efficiency. 89db will do. Rear-ported monitors, corner-loaded can also help with bass, as always.
I'm currently using Wave-8s in my bedroom with Meadowlark Swallows (89db again I think), and this is a great combo also.
I've also used older Bozon Acoustics A60s, again 89db.
You don't need crazy efficiency, just good efficiency. 89db will do. Rear-ported monitors, corner-loaded can also help with bass, as always.