Mesa Baron preamp match

Hi I just aquired a mesa baron which I love but I think I need a different pre to bring out the best in it.I use a blue circle bc21 which I believe has a fairly high gain as does the baron.Any recommendations.I have read the passive preamps like promitheus tvc.Any others with this power amp? What pre are you using?Thanks
I use a Modwright LS 36.5 with my Baron, which works very well. Before that, an Audio Research LS-15, which also worked well. Never tried a passive.

btw, if yours doesn't have the tri-tube mod, you should get it. The Baron really sings with EL-34 tubes, although the higher bias is problematic. The original 5881's, not so much.