Tested my Siemens ECC88 today and it seems to be a slightly better version of the stock tube. Bass was tight, very neutral.
Favourite so far still is the rocket, it's more fun, better bass, vocals sound more alive.
I was planning on selling on one of the rockets I bought from Ukraine but I've changed my mind since it's my favourite tube there is no way I would want to sell my spare ones.
They are cheap enough to get off a certain auction site.
The ones I ordered from Ukraine are 78's so 2 years older than the 80 I got off Mike.
So they should be even better (not tested them yet). Will do tomorrow hopefully.
I'll keep the Siemens and Stock tubes just as backup. But I don't really plan on using them much tbh.