Lite Audio GA-31a phono preamp, is it a clone?

Did you get it from here?
https://www.hifi-amplifiers.com/en/lite-audio-dac-phono-stage-mmmc-c-89/lite-ga31a-tube-mmmcmoving-c...

If so, seems like a nice price. I'd say that's a win if it's reasonably quiet and performs as intended. 

I would give the stock tubes a chance, before putting costly NOS tubes. Also, there may be just one slot where rolling tubes makes a noticeable difference.

I'm not qualified to interpret that schematic, perhaps noromance  or someone else will chime in. 

If anything it's going to be just a pair(L/R), not all 4 that will make a noticeable SQ  difference? You can always just experiment when you get it. You'll be out just two pricey tubes instead of 4.