I would like to elaborate on this.
Brimar vs. Mullard - both ECC82 Square Getter
The Brimar is a bit more forward and cleaner in the mids. Voices seem to sound more real with the Brimar, but guitars sound better with the Mullard. The Brimar has better extension up top and bottom, with the top end perfect and never harsh. The Brimar has less bloom in the midbass than the Mullard, and the bass is tighter and deeper as a result. So, overall I prefer the Brimar, for multiple genres of music. However, with some acoustic stuff, like Rodrigo y Gabriela, the Mullard is stunning and takes the lead. In the end they are both killer tubes, but the Brimar is staying in there, for a good while. Now, I need to find a backup Brimar.
Both tubes still need a bit more burn in, but I don't see much changing.
Happy Rolling!