KEF Reference 3 or Raidho X2?

The difference between X2 and XT2 is simple.  X2 uses a ceramic driver.  XT2 uses a ceramic and titanium driver.  The titanium driver is clearer and will deliver more detail.  
Whether it is worth the upcharge is debatable and is driven by personal
philosophy and quality of equipment you have driving them.  Are you focused on ans listening for small details?  Is your equipment equally brilliant?
This will show up in inner detail with massing of strings in classical or separation of a drum roll.  
You mention an ARC preamp whic will be fine.  Not sure what power amp and tubes you are using along with cabling.  This is a level of speaker where cables matter and the difference between speaker will be more pronounced with a good cable.  DAC also matters here as it can be limiting. 

I recently replaced a pair of Spatial Audio X5 with KEF Reference 1's. The 1's are far less fussy for proper setup, and to my ears and in my room (and with my gear) they image better than the X5's. The image is larger, more enveloping, and with a better sense of the recorded venue. They are also more authoritative but without being aggressive or in your face. I am experiencing no fatigue from long term listening. Low frequencies are surprisingly satisfying without the usual upper bass exaggeration typical of monitor-type speakers. Amps: Jeff Rowland 535.

I know you are not considering the X5's but it is the only direct comparison I can offer. 

Great thread!

I’ve pretty much decided to get either the KEF Reference Ones or the Reference Threes.

JD

@verdantaudio, highly appreciate your professional advice.
the gears I have as follow:

Power AM: Audio Space AS 6i with electro-harmonic KT88 EH tube x 4; National 6SN7 tube x 2; Sovtek 6SC7 tube x 2.

DAC: Marantz SA 10

Cable is from USA recommended by Audio Space which is a manufacturer and wholesaler of vacuum tube amplifier based in Hong Kong.

Wonder if the above would be able to support XT2 to bring out the details? Or, would it be better to settle with X2?

Hope to hear from you again.

Learnt a lot from this discussion. Thanks so much.

We have a ton of kef experience 

The ref series are rather remarkable they do multiple things well they throw a large and well focused soundstage they  have vert good resolution they can play reasonably loud they are not hard to drive they have accurate sound

Dave and troy
AUDIO INTELLECT NJ
KEF FULL LINE DEALER