ARC Ref virgin

I'm potentially going to purchase these monos which will be my first tube component. 
It has new Sovtek tubes; are these ok & a good match for the amps?
Is there a superior tube for these monos? 
What exactly is happening with biasing? 

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My experience is "beware"!  Study and search the forums. 

It may not be for you.

A tube will suddenly fail as some time, and at a minimum a resistor will burn up, or worst case the amp will go up in flames!

This will ether cause great angst, or you will realize this as normal, and be welcome to the world of tube power amps!
I owned an ARC CL-60 tube amp which I traded for a new VT-100. It, apparently, had a bad 6550 power tube (discovered by dealer the next day). I had no idea something was wrong. The point is losing a tube doesn’t always mean a catastrophe.
Good luck with those fine tube amps!
P.S. What is the rest of the system?
@don_c55 - is that normal tube amp activity or model/tube dependent? 

@dweller - Pass XP-20 pre but as yet undecided on speakers.. possibilities are the new PMC twenty5.24, Wilson Benesch Vector, My Audio Design Baron.

There are plenty of choices of amps that don't suffer circuit damage when a tube fails.  Many amps are easy to bias as well.  ARC amps don't meet my expectations.  
If you haven't yet decided on what speakers you'll be using, it's probably premature to choose an amplifier. Given that you've never owned a tube amplifier before, what led you to decide on buying a Ref 210?
I wouldn't rule out a Pass amp. Do your research regarding heat, tube life and cost to re-tube. ARC makes wonderful - great tube amps, but not for me. I'll stick with my Pass amp with a tube preamp. 
adg101 is right. It's usually the norm to use a great tube preamp with any number of SS amps (sticking with mono amps is a good plan). I've had my eye on a Pass 250.8 (stereo) and Pass 100.8 (monos).
@rhljazz - what don't you like about ARC amps?

@cleeds - I initially wanted a speaker upgrade but the opportunity of the deal that was presented unfortunately required the sale of my GamuT M250i mono blocks (I haven't sold them yet) so I wanted to replace them with a good affordable alternative on the used market. I've heard good things about the Ref 210 & always wanted to try tubes.

@adg101 - why don't you like ARC amps?

If an output tube fails would you rather replace the tube and a fuse or send the amp out for repair?  That's what I don't like.  Plus some ARC amps are not user friendly for bias adjustment although the Ref 210 appears to have a user friendly bias adjustment.
To make it explicit, I think rhljazz is alluding to ARC tube amps having the tendency to blow out a resistor and sometimes a capacitor when a tube fails (which they do), necessitating repair after a "normal" maintenance event in a tube amp's life.

I know I sold off some ARC Classic 120 mono's that sounded just wonderful, but I sure got tired of the trip to ARC for repair when a tube went out (and they had a lot of them).  It seems that the ARC design philosophy still allows for this weakness.
I believe the ARC design team feels fuses on output power tubes cause an unacceptable loss of sound quality in their amps. They prefer to sacrifice a resistor (or more) to protect the rest of the amp rather than sacrifice the loss in sq they have found fuses to cause in their amps. It is up to the consumer to decide if they want to own and maintain an amp so designed. There are, after all, other real good sounding power amps which DO have fused output tubes, not requiring repair every time a power tube fails!

 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.

I suggest a used Ref 150 or 150SE. IMHO both will outperform the Ref 210s in virtually all areas except dimensionality in which monos always beat stereo and perhaps (not really sure) ultimate power if you play at 100dbs which I never do. I had the Ref 210s in house against the Ref 110s and the 210s were perhaps 10% better in only one or two aspects that matter to most listeners at normal or even fairly loud (say, 95 dbs) listening.
The biggest improvement over the 110s by far was in stage width and depth----again---perhaps 10%. But since ARC is famous for that very characteristic, among others, I  felt I had enough with the Ref 110 and went with it at the time due to the cost/value relationship.
Having since moved on to the Ref 150 and then adding KT 150s a year later, I can say without qualification that the Ref 150 and 150SE downright smoke the Ref 110 and 210 monos. The difference being more in the range of 25% or more precision, transparency, palpability, texture..I could go on and on. I would go so far as to say that it is my favorite ARC component of all time---and I've had a few.  In comparison the Ref 210s lack drive and are a but whispery in their presentation.
Read the reviews of the Ref 150 when it came out and you will be able to glean from the reviews this same conclusion re the latest generation of ARC amps being far superior in most important aspects relative to the prior generation.