That’s been the problem with EH for quite a while now. They sell what they get and what they get is all over the place. And not just by a few mA.
In the past, we specified an Ip limit on tubes we purchased from them - usually no less than 30mA and no more than 50mA - and they complied.
Since 2020 they’ve revised their policy and no longer accept a limit on Ip. As a result, we were seeing everything from 15mA to 75mA. No adjustable bias configuration can easily compensate for a range like that. Now we only buy very limited types from them.
The EH KT88 production was interrupted during this time so we switched to 6550. There hasn’t been a drastic difference in performance, so even though the EH (or any other Russian brand) KT88 is back, we’re not buying them until they reinstate the customer Ip spec policy. JJ KT88s never sounded that good, so we didn’t switch to those.
We currently use Psvane, JJ and Sovtek 6550s in that order of preference.