Low volume listening dynamics

If you are going with very low power you may want to consider speakers as effecient as possible. I have a pair at 106db.

A high sensitivity speaker may or may not be more detailed than a low sensitivity speaker. The most detailed speakers are ESLs and they are not so efficient. 
The problem of listening at low levels is that our ears sensitivity to bass and treble is greatly diminished so unless you have some way to compensate for this low level listening is always going to be low fi. 
Compensating for this means loudness compensation for the volume you like listening at. Only a digital room control system with the ability to create custom target curves can do this effectively. 
The other solution is.....just turn it up:)

I am running Klipsch Forte III's (99db) with a First Watt F7 (20wpc) and the combo sounds great at low volumes.

Yes only as good as the first watt! So do you have an idea of the db level your trying to archive at low level? I have a pair of Magnepan 0.7's that have a lot of inner detail/soundstage and are driven by a high watt/current D class amplifier that is very musical to say the least. I normally listen around 72 lb with a few peaks depending on the music With all that wattage and current from my amp the music still has dynamics and energy, even at lower levels 

I listen to music at a relatively low volume, but I still want the clarity to hear the details.

I'll take a different tack from most of the posts here. The most important thing for clarity at low volume is the room. What is the background noise level? Has bass overhang been controlled? First reflections? Slap echo?

The cleaner the acoustic, the more detail you will hear.