I am in the camp that Cyro (on TUBES) does make a difference. At first I thought how can CRYO process improve the sound. As a side note, where I used to work (Space and Satellite) R&D / Manufacturing, we use CRYO machines to change the metallurgy molecular structures of components for the programs we build. So CRYO is not snake oil, but proven to work for certain Applications, BUT for Music? Hmm.
So, a Friend and I purchased 2 sets of the same tube, one CRYO and one not (SED winged C EL34) and did the proper break in on both tubes. when the time came, we listened and boy, we hear a difference, Not Night and Day difference but there is a difference.
To me, if you have a resolving system (which we had) CRYO may? make sense. If not resolving enough, dont bother. just like speaker cables and power cables. it all depends on synergy and weakest link.
That's just my opinion.