For all those looking around for OG EJ07 there is apparently OEM of them in Yinyoo ST7 for much lower price at certain occasions (600$ incl. VAT).
https://m.pl.aliexpress.com/i/1005002900712128.html?gatewayAdapt=Pc2Msite
Some measurements were taken by head fi users https://www.head-fi.org/threads/shuoer-impressions-thread.916267/page-147
It was on sale on Polish forum once for ~400$
Edit: thread from hifiguides on them: Yinyoo st7 4est 2ba 1dd 10mm
Michael Bruce review:
https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DrN6ombhWZy8&ved=2ahUKEwiW5Yf5sPz0AhVqw4sKHSgRC6cQjjh6BAgYEAI&usg=AOvVaw3xRVI_zTGHBIepfvNARYXZ