KEF Reference 3 or Raidho X2?

The first thing I would ask is whether you intend to purchase either speaker un-auditioned ? Asking others for guidance or opinions is not really the best approach. Unless you have a lot of cash to throw around, I strongly suggest that you make arrangements to audition both speakers. I realize this could be a challenge. Locating a distributor for either of your for mentioned choices can be very difficult. Especially in the case of the Radiho. I think their dealers a few in the US, unless you live out East. In New York, for instance, I'm certain you will find a dealer for both brands.
From that point on, "use your ears". This the only true way you can solve this choice issue. Personally, I don't feel that either one would be on my short list, but that's me !

@verdantaudio, thanks for your valuable info again.Would you please advise if there is a real difference btw Raidho X2 vs XT2. Is it worth the extra money to get a XT2?
I have auditioned both X2 and XT2 but in different studios with different gears so it is difficult to hear their differences. 
Looking forward to hearing from you.

Hello,
I really appreciate the Raidho dealer giving an honest opinion. Thank you Verdantaudio for that. I have only heard the KEFs. I actually prefer the REFERENCE series to the Blades. Only because you need the right room for the blades. Putting KEFs on Hegel helps keep them in check. That being said you might want to look at the KEF Reference 1s. They are still a three way speaker and with the stands you can save yourself $4000 over the Reference 3s. That will get you a couple nice subwoofers if you need them. You might not. They are probably one of the best speakers for getting good clean bass. You don’t need 175 watts, you just need the watts to be really good like from Ayre or Hegel. 100 watts will more than cover for what you need. Don’t get me wrong the Reference 3s are amazing. So is a new Ferrari. But if you have to drive that Ferrari 25 mph all the time it’s a little over kill. Another tower you might want to look at is the PSB T600. With the 5 way crossover and IsoAcoustic footers the sound is controlled and the cabinet is about 90% as perfect as the KEF Reference 3s for $8000. They are like having a KEF Reference 2s with a better tweeter and crossover IMHO. The PSB speakers are not for everyone because each driver is crossed over in a tighter frequency range. I use two of the JL Audio F110 subs and the CR1 crossover. If I remove lets say below 70hz from the PSB the bottom driver might not even play. When I did this with the KEFs all the drivers were still playing due to the larger frequency crossover range.  So as long as you are not cutting off the bottom frequency’s yourself I say go with the PSB T600 or the KEF Reference 1s with those beautiful matching stands. I would add the IsoAcoustic Gaia 2s to the KEF Reference 1s and fill the stands with sand or lead shot. This will cost you another $800. On the Reference 3s you should go to the Gaia 1s because of the 114 lbs. 114 lbs is too close to the
120lbs limit of the Gaia 2s. They say 10% less of max is preferred.  That will cost you $1000. Now you are up to $15,000 for the Reference 3s vs $8000 in the PSB T600 that come with IsoAcoustic footers. This store in the Chicagoland area will let you demo the KEF and the PSB in your home:
https://holmaudio.com/
Don’t get me wrong. I love the REFERENCE 3s. But, Do you have the space to drive them. Sometimes people forget these are Ferrari’s. Bigger is not always better especially when it comes to the room. 

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.