Welcome!

The short answer is I have not tried the 7189, but I did listen (briefly) to some other EL84 types and wasn’t impressed, so your experience is interesting. I’m curious if you are comparing them to Decware 6p15p tubes, or random ones off the internet? Because I find a huge variation even in 6p15p tubes from the same factory and same date, much less between different versions e.g. 6p15p-ev and 6p15p-er plain old 6p15p.

Just an update for anyone who cares. The 6p15p tubes I received from decware were clearly much better than the originals I started with, even though they were apparently the same brand. They may be an upgrade from the 7189's even, but I wouldn't say they significantly outclass them sonically. I suppose this is confirmation of the variety in quality of 6p15p's out there.

The Decware tubes I received say -EB on them.

FWIW, the Tung Sol 7189's are also Russian military spec with enhanced features (higher plate voltage and clean headroom) over EL84's. They make for great backups to the Decwares if nothing else.