Reasonably sensitive speakers for tube amps, max $2k/pair, new or used


While this topic has been covered before, I'm interested in both recent experiences with new products or anyone who just would like to chime in.

I have a couple friends interested in tube amps, lower wattage -- 40 wpc or below. Before they pull the trigger there, they need to find the best higher sensitivity speakers they can, hopefully at $2k or below, new or used.

QUESTION: What high sensitivity speakers would you recommend to them, new or used? What did you try and NOT like?
Characterizations of their sound, experience with a trial period, the company, etc. appreciated.

I'll pass the best answers and links along to them.
hilde45
+1 for Zu Dirty Weekends - I run them with a 15 wpc Cary 300B SET integrated.  The DWs were $1K with the base finish when I bought them 15 months ago.  I team them with a pair of SVS SB1000 Pro subs which were less than $1K.  This is a nice $2K combo that sounds excellent with acoustic, rock, blues and jazz tunes in a smaller room...15x15.

The DWs also sound wonderful with an 18 wpc First Watt SIT-3, which is solid state but has some tube sonic qualities. The SIT-3 is used primarily in my main system with a PrimaLuna tube preamp running Belle Klipsch speakers and a 2x12 SVS sub, but in a much larger room.

I also have a pair of Heresy I's and a pair of Heresy II's which both shine with these amps and can be found for under $1K online.   These, also matched with a sub, would sound great with a tube amp, but not as nice as the aforementioned Heresy IIIs or IVs but easier to locate at a reasonable price.  Bob Crites has updated crossovers etc. that can help to modernize these older unit. 
Forgot to mention that the Heresy's are listened to on Target stands, not floor risers.