The SFL-1 is far from rolled off in the HF's, but if your Brimar's are from the 50's production they may help.
If not (later Brimar versions are cleaner/crisper) look for older RCA Black plate 12au7's, assume they are not pricey, but have not purchased any for years.
My best advice (for the sound you seem to be seeking) would be to go with something other than the SF preamp.
Most SF and ARC preamps/amps are not my cup of tea as I prefer a more fluid sound.
This said, I've heard them sound super on both home and store setups, just not the type of sound I care to listen to on a day to day basis.
If not (later Brimar versions are cleaner/crisper) look for older RCA Black plate 12au7's, assume they are not pricey, but have not purchased any for years.
My best advice (for the sound you seem to be seeking) would be to go with something other than the SF preamp.
Most SF and ARC preamps/amps are not my cup of tea as I prefer a more fluid sound.
This said, I've heard them sound super on both home and store setups, just not the type of sound I care to listen to on a day to day basis.