Late to the party but have some info that might be of interest, I hope.
Bought 4 Brimars after reading all the great reviews about them. There was almost only one bad one and that was the same as I found them - muffled with much more bass. The guy that reviewed then said he thought it had to do with his set-up and I assume that goes for me to.
Opera Consonance Reference 8 player
Swapped the Brimars for Siemens, NOS as well. Much better but when compared to the Psvane Art Line I have been using for a short while - not as good.
All this is said with the tubes not being burnt in properly. But my favourite so far are the Psvanes.
Will probably try out RCA Clear Tops as well when I can get 4 at a good price.