I RECENTLY PURCHASED A 190L HEAD FROM A MUSIC STORE FOR $165.00 GREAT SOUNDING HEAD. SOMEONE HAS PUT A MASTER VOLUME ON THE AMP WITH THE POT MOUNTED RIGHT IN THE CENTER OF THE SUNN LOGO. WORKS GREAT FOR TUBE OVERDRIVE. ANY INFO AVAILABLE ON THE HEADS? IS THE CIRCUITRY BASICALLY THE SAME AS A SOLARUS HEAD? I ALSO OWN 2 OF THESE A 71, AND A 69. I PLAY THEM THROUGH A SLANT FACED LANEY 2X12 CABINET LOADED WITH CELESTION GREENBACKS. REALLY GREAT SOUND. ANY INFO IS APPRECIATED.