@tksteingraber Thanks for reminding me of Summit Series, completely forgot, this could be real contender for my next 300B. And I agree the Acme hands down superior to Shuguang Black Treasure. BT and all lower tier 300B simply not up to resolving/transparency capabilities of higher tier 300B.
So, it comes down to Takatsuki vs Summit for my next 300B, already have offer in for some lightly used Taks.
Skunkie Audio over on youtube is in process of building custom 300B amps right at the moment. In the process of building these amps she is measuring various 300B, very enlightening as to power output vs distortion and second vs third harmonic distortion levels. The standard EML probably has best second to third harmonic distortion level measurements in that the preferred second order predominates more in this tube than the others, she also preferred this tube subjectively in her amp. WE didn't measure all that well and subjectively she didn't like sound quality at all. In recalling this, EML standard tube should also be on my to buy list.
She's also experimenting with various power and output transformers, Hashimotos and Tangos amongst some others.