Newb Tube question

NOS tubes are vintage tubes which sound better than new production which mostly come from Russia, although these tubes have been improving over the past few years.

The Project website states that the Tube Box S2 phono stage uses ECC83 tubes which is the European designation for 12AX7 tubes. These are widely used in audio components.

The following website provides good info on the different manufacturers and a description of how the tubes sound. Lower down on the page are the tubes for sale. There are many versions of 12AX7’s which include different plate types and internal tooling.

http://www.audiotubes.com/12ax7.htm

First, you need to decide what is lacking in your music and how you want to change it. For example, if you want more detail or more extension in the bass, or if you want a warmer presentation, you can select tubes with the appropriate characteristics or timbre.

 

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.