It's not terribly important. I'd just look for two that have the same internal construction.
Thanks Doc, that makes things a little easier.
A few weeks ago I was reading some posts over at the Decware forum pages and Steve D mentioned the Guiguang as the cheapest 300B he could find. He tested them in his new Sarah 300b amp and was quite impressed with them for the money. With the thought in mind that the 2A3 is a very similar design to the 300B, I looked them up on AliExpress. There seems to be one seller listing a couple of versions of the NOS Guiguang 2A3C. As it turned out, I'd bought from this shop before and had a good experience. The seller knows his stuff and tests/matches his tubes. Yes, he actually does have a tube tester! He purchased what seems to have been the last warehouse stocks of the original Guiguang factory supplies of these, so they are dwindling. I grabbed a pair and they took just a week to arrive in Oz from China, free shipping too!
I've had them in the newly built Stereomour II for a few days. (By the way, the S-IIis the best amplifier I've ever heard, and Kim agrees. She says we should sell our A50/300B now!) Anyway, compared with the very smooth and laid back Psvanes, these Guiguang 2A3Cs sounded rather edgy, coarse and shouty. Anyway, I left them in the amp as I was just listening to local radio and Radio Paradise at low volume while I worked. Two nights ago, Kim and I settled in with a nice bottle of local Shiraz for some serious listening. The speakers I hooked up were our favourites, the 15ohm Leak Sandwich Minis and we played, Dire Straits, Diana Krall's Turn Up The Quiet, Sil Austin, Ben Webster, and a long time favourite, Brubeck's Last Set At Newport. It was a mind-blowing experience, because suddenly these Guiguangs seemed to have come to life. Gone was all the edginess. The mid-range was smooth and lush, the bass was musical and tight, and the highs were crisp and sparkling. They were everything we look for in a nice power tube really. I'm comparing them with our TJ Full Music 300B Mesh Plates in our A50, except this S-II amp and Gui 2A3 combo does it so much better.
This morning, I ordered another pair, as these NOS 2A3Cs will be gone forever when they run out. They don't break the bank and they sound insanely good. Now, how long they will last, I have no idea. But at this price you can buy a few pairs and still be in front of some of the pricey offerings out there!
I just thought I'd share this experience with those who might be looking out for an excellent sounding 2A3 for their S-II for not much money.
PS. Note that there are two versions of the Guiguang 2A3C. One has a white ceramic base with gold pins. The other has a black base with silver pins. I'm not sure of any other differences, but the one I reviewed above has the white base and gold pins.
PSS. The seller advised that the only difference between the two Guiguang 2A3C types is the silver pins and the black base, otherwise it’s the same tube.