Looking for speakers for my 4W SET amp


I'm looking for some speakers with very high sensitivity for my 4W SET amp.  This is for a 2nd system so I'm not looking to break the bank.  I'm looking into Zu Omen Dirty Weekend, Omega Junior XRS or maybe a DIY project with Audio Nirvana or Lowther drivers.  I've never owned single-driver speakers before and I'm a little nervous to take the plunge.  Any thoughts?

thanks!
adam8179
thanks to everyone who contributed to this thread.  You've given me lots to think about
4W is tough
4W is more than enough, assuming that you select symbiotic gear and aren't trying to play in a concert hall-sized space.

My 45 Triode monoblocks put out 1.5Wpc and play plenty loud in my living room.  How many enthusiastic owners of decware UFO amps think 1.7Wpc is all they need?

You do need to pay attention to all the things gsm18439 listed.  As many have reported, I don't find that SET amps to be best for some musical genres like (obviously) heavy metal and techno.  Music with "too many notes" like large orchestral pieces are harder to get right on most/smaller single driver speakers.  But I have never heard a system that was perfect in every way.  Have you?

I have not heard the The TU-8200.  I have heard the TU-8600 (300B amp) and it is a terrific amp for the money.  I am a fan of the 6L6 tube, so I would bet that the TU-8200 is a winner.  I hope you find something that it will drive to a satisfying level.

From my experience, the kind of music that is hardest to achieve a satisfying or realistic listening level with low-powered amps is choral music, particularly acapella choral music.  At surprisingly soft subjective levels, the music seems to fall apart.

You are probably on the right track looking at Zu speakers--they are fairly efficient and easy to drive.  Zu's are very punchy sounding speakers; for some reason, the Zu representatives show them only with solid state amps, so I have not heard them used with low-powered tube gear.   Audio Note AN-K are nice speakers that are also not crazy expensive (they are warmer and more relaxed sounding than Zu speakers); I've heard them with fairly low-powered SET amps (7.5 watts/channel) and with push-pull 6L6 amps and they sound good. 

I have much preferred Lowther drivers used as wide range drivers (used as a midrange), rather than as a full range driver, but, they can be terrific as fullrange drivers in back-loaded horn systems.