Never Owned a Tube Amp and Want Advice

There are good points about how much tube power you will need for your speakers.  They may not be a good match.  High power tube amps can be noisy, of course there are very quiet well made tube amps with 50 watts or more but well made and quiet tends to be expensive.  If you have the money go for a good one.  
Starting with a pre amp and SS amp may be an  easier way into tube sound and you speakers may be happier.  The Decware CSP3 is a very nice tube pre amp.  Decware also make very nice tube amplifiers.

Be8ng new to tubes my advise, Look at Ayon ,Why they had made in Austria Great build anti resonance machined aluminum not sheet metal  great Lundahl transformers very important for Fidelity 
most important, tube Safety ,Ayon has a Smart bias which is microprocessor controlled, you hit a button a few minute check 
it monitors wear and keeps each tube at optimum range under 80% of max last longer ,and if a tube goes bad ,not like some wear they glow red and explode or poor weak tube it Automatically goes into mute if a bad tube is detected
and you unplug ,or if not in the room after 15 minutes Automaticlly
Shuts off, on back indicator tells you which tube has the fault 
shut off 15 minutes ,replace tube ,turn on wait 15minutes to get up to temperature ,then hit rebias button volume off . In 3 -4 minutes 
processor calibrated blinking Ayon logo stops blinking ,ready for music .  Rebias check 1-2 months the best biasing system 
on the market I just bought another the spirit $5 is the new best of at around $5k the triton is the power house, for the average person 
the new Scorpio xs around $3100  USA tube audio 
is very good answering questions you may have the spirit I have older one 8 years old still runs perfect.

Another great thread, very informative! 

OP, what is your preamp?  Didn't see that mentioned anywhere.  My suggestion would be to get yourself a good tube pre and see how you like it with your DNA 500.  I'm using a DNA .5 (100 watts) with a Rogue Perseus tube pre and very happy for now.  Started small and cheap with a Schiit Saga tube pre which sounded good but knew I could do better.  As you've probably read here and elsewhere this could be the best of both worlds for you and a worry free entry into tubes (no biasing, etc.).   

I do have a Jolida 502b tube integrated (60 watts, Gold Lion KT88) that I used for years and still do occasionally.  The Jolida definitely gives you more of that "tube magic" but the .5/Perseus combo gives better bass control and punch.  

BTW, my speakers are old Snell Type D (rated at 87 dB and 5 ohms) and  not quite so old Gallo Ref 3.1 (88dB, 4 - 8 ohms?).  The Jolida powers them both quite satisfactorily for me in the 80 - 90 dB range.  Although, the Gallos do seem to play just a bit louder/cleaner before any hint of distortion.  I am very interested in trying some speakers over 90 dB with the Jolida.  Unfortunately, can't afford any Tannoys right now!  ;-}

Keep us posted

+1
@pkatsuleas My suggestion would be to get yourself a good tube pre and see how you like it with your DNA 500...

@dsper
Exactly. If you like separates, try this for a while if you want to learn and appreciate the differences a little more.   Allows you to leverage your current DNA-500 on the back end for a while. Add a really nice tube preamp on the front end. Get some good input/driver tubes. Still a bit 2D sounding, but it gets you half way there and its fun to learn how half tube and full tube sounds. 

Then curiosity about full 3D tube sound sets in for some after hearing the tube preamp in the loop awhile with SS amp on the back end. At that point, start eyeballing your future tube amplifier and decent interconnect cables to go along with the all tube setup.  Doing this in steps is fun too.

I own a tube amp and a ss amp. Swap them out to hear the differences and enjoy both greatly. Tube amps are more 'hands on' than ss amps IME. Tube amps also have a few idiosyncrasies that ss amps do not,IMO.
Firstly, what is not really mentioned here ( at least that I could find) is that tube amps are generally more costly to run. One has to budget for expected tube replacement. Also, typically IME the amps run hotter than ss amps. ( particularly Class D ss amps) So, if heat is a concern, and it should be in many parts of the world today, then this needs to be considered. Then we have the biasing scheme required by most tube amps...( unless they are self biasing, which is the way I would STRONGLY recommend you go). I used to own an incredible sounding tube amp, but the biasing protocols were bordering on criminal! This is less common today, but still something to be very much factored in. 
Lastly, expect a tube amp to require more warm-up than the typical ss amp. With a lot of tube amps one has to wait for the tubes to stabilize before listening to music, that generally is not a factor with ss amps. In case it sounds like i am down on tube designs, absolutely NOT, but one has to expect their 'requirements' to get the best sound. ( and that sound is one that I generally think sounds better than the best ss amps, at least that I have heard!).