Hi Paul,
Take my word on this one, neither of the tubes you mention come close to the sonic performance/beauty of the 12AX7 equivalent 5751 NOS tubes. They are really quite reasonable priced and have replaced in my system my very expensive NOS 12AX7's in my DAC. I would recommend you try the Sylvania Gold Brand Gold Pin, the most expensive, or for less then a 100 dollars a pair the RCA Black Plate Triple Mica's or at very low prices the GE Black Plate Triple Mica's. There many for sell here on the GON and beat the pants off sonicly either tube you want information about.
Take my word on this one, neither of the tubes you mention come close to the sonic performance/beauty of the 12AX7 equivalent 5751 NOS tubes. They are really quite reasonable priced and have replaced in my system my very expensive NOS 12AX7's in my DAC. I would recommend you try the Sylvania Gold Brand Gold Pin, the most expensive, or for less then a 100 dollars a pair the RCA Black Plate Triple Mica's or at very low prices the GE Black Plate Triple Mica's. There many for sell here on the GON and beat the pants off sonicly either tube you want information about.