Reflektor tubes in Audio Research Reference SE

Would a pair of NOS Reflektor 6H30's from 91-92 be a significant change or upgrade in the input stage of an Audio Research Reference 75 SE? or insignificant?
Listen and find out i don't think so.

I ordered a matched pair, and will let you know what I hear. Hopefully good things, at $500 for two tubes. 1981 date of manufacture.
After listening for a couple months, and swapping back and forth, I consider the tube change quite significant. The Reflektor tubes, along with the Synergistic Research Black Quantum fuse are the most significant upgrades I've made, even more so than the power cord. The mids are smoother, and the highs are cleaner. More crystalline. Quite an improvement on piano realism. I'd say, for about $650, the change was well worth the expense.