Recommendation for Good Quality Desktop Speakers

I am looking for speaker recommendations for near field listening when i'm sitting at my desk. I have a 8 Watt tube headphone amp for power. I currently have NHT (H:12" by W: 71/4 by D: 9") speakers on either side of my 26" screen. I'd like to stay within the current speaker dimensions or smaller. I sit 30" from the screen. This setup is ideal for late night listening. I've considered Harbeth P3 ES2 or something at or under $1,500.00.

Thanks for your thoughts.

Passive version of KEF LS50. Not sure if your amp can drive it tough. Used prices are coming down now likely due to the active version of the LS50 being available. I use it on my desktop with a $480 ebay Parasound A23 amp. My KEF's were $1100 used 3 years ago. You can get them much cheaper now. I do a lot of late night listening in my office while i work. They sound amazing nearfield.

I also want to get the active version of the LS50 for another room (desktop like setup there too).

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I upgraded from the Audioengine 5+ to the Audioengine HD6, and I use the Audioengine S8 sub along with the Audioquest DragonFly Red.  I highly recommend you take a look at these. Be sure to read the specifications and advanced features the HD6 has.
The New Proac Tablette 10 is very tube friendly
  offers an ideal 10 ohm load, are sealed for close wall placement, and sound incredible with many decent amps.
 Proac Dealer
Silverline Minuette Supreme are very compact and musical. The Kef LS50 is very detailed and forward...if you are like me, this would sound great at first, but eventually fatigue you.  
I've been using for several years the JohnBlue JB3 single driver speakers in a similar setup with a 10 watt El84 tube amp. Obviously, if deep bass extension is important to you this isn't the gear you'd want but for near-field listening it's very satisfying.
Hi -- I am thrilled by the desktop speakers I have been using for about three years. They are Audience Clairaudient "The One" speakers, and are only about 7" high x 7" deep x 5.5" width. They are single drivers so throw a great soundstage at a short distance.

The are not incredibly efficient at 84 dB, but will be easily driven by your amp at late-night listening volumes.

Clairaudient also has upgraded versions with the V2 designation. And it makes the slightly larger 1+1 desktop speaker that is many an audiophile reviewers’ desktop/mini speaker reference. Both have won several awards. 

I find them truly small enough to be a desktop or bookshelf speaker with excellent dynamics and a non-fatiguing sound. Worth a no-risk audition.