Newb Tube question

Having recently acquired a Pro Ject Tube Box S2 phono stage, I'm liking what I hear and am wanting to learn more about tubes.
I see reference to the plates inside the tubes... "short plate", "long plate", "smooth plate", etc.
Is there any sonic difference with the different plate characteristics, or is the quality and manufacturer more important?
Are there brands to seek or avoid?
Just curious... Don't know if my lower-end *system or my 65 year old ears are capable of resolving the difference between tubes anyway.

Thanks!

*System:
Emotiva BasX PT-100 preamp, Emotiva BasX A300 power amp, Zu Libtec speaker cables feeding Maggie 1.6's, Morrow interconnects, Technics sl-1200 mk2 w/ Nagaoka mp-200 cartridge and before-mentioned Project Tube Box S2  phono stage.