Newb Tube question

Your 65 year old ears will be able to hear the difference if you're a critical listener.  I'm 63 and have significant hearing loss (so I listen at an elevated volume) and I am able to hear things I would never have believed, and it's because I'm a critical listener.  When I listen, I sit in the sweet spot in a dark listening room so I'm not distracted by anything.  My attention is focused on the music, i.e., there are never any other thoughts running around in my mind, I'm totally fixated on the music.  My listening pleasure comes from, as an example, hearing every nuanced expression in Etta James' voice (in my opinion that woman's vocal chords are connected directly to her heart).  During one listening session, I heard something change in her voice and became worried there was something wrong with my audio gear.  (FYI:  IF I had been listening to the music as "background" music I never would have noticed a change in her voice.)  I put on a CD designed to "break in" audio gear and selected the track with a frequency sweep form 20Hz to 20kHz.  As the pitch began to climb I heard a very slight "rattle" coming from behind my speakers at around 400Hz.  I walked back there to find I had placed the steel top plates of my mono bloc amps (which I had removed for additional cooling) leaning against the wall on top of each other.  As the frequency swept through 400Hz they began to softly rattle and then stopped as the pitch continued to climb.  I laid them flat on the carpet, put Etta James back on and was totally relieved when her reproduced voice was back to normal.  I'll give you an example of what critical listening is for me.  A friend asks you (or me) to take a ride with them in their car to help them identify a noise they hear.  After driving around for 20 minutes listening to your friend say "it's kind of like a chirping sound coming from the front right tire", you finally hear it.  Now you're trained to hear it, and each and every time you get in your friends car you hear the sound without effort.  So how is that like critical listening?  The by-product of sitting in the sweet spot and listening to every nuance of the music is that the "training" happens naturally.  Once you're used to listening to the detailed expressions of a female vocalist (for example) it comes without effort each time you sit down to listen.  My point in all this is that the "training" I'm referring to happens even if there is significant hearing loss, as in my case.  Are there things I can't hear?  Undoubtedly, but I can easily hear the difference between audio electronics, and, if you're a critical listener, you'll be able to as well.

+1 for Brent Jessee http://www.audiotubes.com or Kevin Deal at Upscale Audio.

Brent Jessee has a good description of the general characteristics of various tubes that I found helpful

I am about your age and a relatively recent tube-a-holic!  I think I love them because some are older than I or at least the correct generation.  I found the following write up / review to be very helpful although I do not agree in any way with his blanket indictment of 12AX7 tubes...having run them all I have some favorites.  I also found Brent Jesse's website to be a great wealth of information.  Have fun and enjoy the journey!

https://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html

OP;  I concur with the above comment about critical listening. During a listening session, even if you have high frequency hearing loss, you can discern the differences between tubes. Some are very obvious such as Telefunken (wide open transparent image, very dynamic) vs. Mullard grey plates (warm with a rolled off top-end). 

I love tube rolling and now own an all tube system; amp, pre, and dac. I can hear the difference between each tube swap so I'm sure you'll be able to hear the difference in a single component. 
My recommendation is to try NOS tubes which have extended highs and cast a wide soundstage. Get as much high-end information as possible from the tube since your hearing is causing a high frequency roll off.

Sylvania tubes have high-end energy, good detail and a transparency that is very revealing. RCA blackplates have lush sonics with a wide,  deep soundstage.
IME, you will not hear drastic differences between the new production tubes made in Russia. They don't have the different flavours as NOS do.
 
 

Thanks to all for a compendium of great advice and resources.
I'm very happy with the way my tube-phono stage and upgraded stylus sounds..to the extent that I'm going through my vinyl collection, enjoying the adventure of hearing new, better details and color in acoustic instruments and voices. When this blissful stage has run it's course, trying a different set of tubes or two will be a fun way to tweak the sound without breaking the bank.
Without your great suggestions I wouldn't have had a clue where to start.

Sincerely,
Mark