Which Preamp Audio Research LS3B or Sonic Frontiers SFL-1

Hello-- I am looking replace (upgrade) my Nakamichi CA 5 with either preamp in above title line.
Does anybody have either (or both) of this classics? Which sounds better? My current system is as follows:

 Amplifier is a Sunfire 300 x 2
 CD Transport is a McCormack SST-1
 Universal CD Player is a Lexicon RT-10
 Jitter reduction is a Genesis Digital Lens
 D/A Converter is a Classe Audio DAC-1
 Finally, my speakers are a pair of JBL XPL 140A's

I know if I go with the ARC LS3b I can go Balanced with Sunfire;  but, can that 1 tube in SF SFL-1 make the system sing. 

Any assistance before I decide to take the plunge would be greatly appreciated.

Regards,

Edward