From a technical perspective, will the Ref 6 work well with the Jeff Rowland 625 S2 amp?Richard, I see no technical problems mating the Ref 6 to your 625 S2 amp or the Aeris DAC. However, if by any chance you are still using the SVS subs you had in your system a while back an impedance incompatibility would result, relative to the Ref 6’s minimum load recommendation of 20K (which btw is the same as the minimum load recommendation for many other ARC line stages and preamps).
That would also occur with many other subs that would be connected to the Ref 6’s outputs. I believe that its two unbalanced outputs and its two balanced outputs are all driven from the same output stage. Hence that output stage would see the combined load impedance of the amp and the subs, which would be considerably lower than the input impedance of either. For example, the 22K balanced input impedance of the SVS sub and the 40K balanced input impedance of the amp represent a combined impedance of (22 x 40)/(22 + 40) = 14.2K, well under the 20K recommended minimum.
Good luck. Best regards,
-- Al