Prices are about $2500 for either of them.
Details of the ARC SP 17L are:
Finally an affordable ARC!
Details of the A.I. L2 are these
but they are making a 2B version in a couple months, and I dont know the improvements, yet.
I do not have nor plan to get an all balanced chain, so the ARC above seems a tremendous deal for me. I'm speaking of new units. There is no convenience to buy an used unit (except maybe the AI L2A), because the ARC LS17 and LS26 are so much of an improvement over previous models.
My indecision is because the AI seems to have shorter signal path, less tubes and external PSU. ALl of this theoretically should provide a more transparent sound.
Note also that the pre WONT be paired with a power amp of the same brand, but used to drive two power amps, one SS for the bass and one pair of tube monoblocks 845 S.E.T. with 0 feedback.