This review page is supported in part by the sponsors whose ad banners are displayed below Generalities: Having been at the 300B rolling game for a while, I've 'categorically' separated the bunch into two classes. I call them classic/vintage and modern. The archetype for the classics is the Western Electric reissue. Cheaper Chinese, the Gold Aero and the standard Full Music as sampled in the gorgeous Emillé Lab's 300B integrated belong into this class too. The moderns are epitomized by the Czech school of AVVT, EAT, Emission Labs, JJ and KR Audio. The Czechs all use thicker heavier glass, stouter pins and often far taller envelopes which in many cases won't fit under tube cages styled for classic valves. Sonically the classics are more fluid, midrange-centric, burnished and opulent as well as bandwidth-limited and dynamically less potent. The moderns have wider bandwidth and stronger bass. They sound more linear and controlled/damped. In trade they give up some ne sais quoi of the classics. It would be astute to say that for classical music, the classic tubes are more compelling for their greater succulence and fleshiness in the timbre domain. For hard-hitting bass-potent modern fare, the tauter more robust and dynamically stouter but also drier moderns would seem more appropriate. Needless to say, none of this factors listener preference. Nor does it the very real influence of driver tubes which often exert more control over the final sound than the designer output glass. On the classic 300B side, the Western Electrics until now were king followed very closely by the standard globe TJ (also marketed as Sophia Electric). Then they were trailed at some distance by standard Shuguangs and various unmarked Sino bottles I've tried. On the modern side and in current production—this eliminates the Vaic and AVVT—the EML 300B XLS and Euro Audio Team rule ahead of the JJ. EML makes a 320B XLS just as did Vaic. Those are not drop-in replacements for most amplifiers. Even in my Yamamoto which can take all the 320B variants, I prefer Jac van der Walle's 300B XLS. The appearance of the Shuguang-built Synergy Hifi valves with Create Audio-supplied proprietary treated alloy cathodes and Shuguang's top-line Black Treasure 300Bs somewhat screwed up my neat categorization scheme. That always tends to be the case for any attempts at shoehorning things into neat drawers and fully slamming 'em shut. Those Chinese tubes have clearly more bandwidth than the classics particularly in the treble. At first that's outright frisky, bright and forward. With use, it eventually retracts to remain benignly lit up. They also have better bass than the classics but aren't outright moderns because of their more fluid and color-intense character. That's less solid and texturally wetter than the Czechs. I think of the Black Treasures and Synergy bottles as the foot-in-either-camp guys. It doesn't make for a snazzy new category so I've left it at that. While Chinese too, the top TJ/Full Music is a classic again. On both build quality and sonics, it's a Western Electric a bit on steroids. This may not hold true vis-à-vis the fabled original WE but with its rarity and silly NOS prices, that's academic to mere mortals. Why Western Electric has discontinued—or temporarily suspended—availability of popular reissues is anyone's guess. That said, the TJ 300B SE renders the question mute. While flatly expensive, it remains a more affordable option than the $1.200/pr which WE reissues commanded when last I checked.