I have a very similar system. Audio Research Ref 5se, Ref 110 and Sonus Faber Elipsa SE speakers.
The Elipsa SEs don't need the extra power of the Ref 210s. i would opt for a Ref 150. Especially for a tube newbie. My Ref 110 has no problem driving them. If i remember correctly, they are rated at 92db..
A tube preamp will make much more of an impact on the sound. If i only had one tube component in my system it would be the preamp. Tube preamps also need a lot less attention. You can always move to a tube amp later.
If you want to replace your amp first, I would go with something solid state like a Pass 60.8. The Elipsa SEs are 4 ohm speakers. The 60.8 is rated at something like a 120 watts into 4 ohms before it ever leaves class A. It also is a superb match with the Elipsa SEs as well as Audio Research preamps.
The Audio Research Ref 110, 150 and 150se are all easy to bias. I have never had a resistor pop in my Ref 110. But it does happen. I have had maybe 2 pop in the last 20 years. It takes a violent tube failure to pop one, not just the normal tube failing. You don't need to send the amp back to Audio Research. Almost all dealers can easily do it in house or have a service guy who will do it.