Barrelchief:
You asked "Are you basing your comments of the Synergy IIi vs. Concerto on a head to head comparison that you have done?"
No, I am basing the comment upon the fact that the Concerto is significantly less expensive than the Synergy IIi, the latter being Rowland's most expensive current preamp.
As for my familiarity with Rowland, I have owned a Cadence phono preamp for almost five years and a Coherence II preamp for a year and a half, both of which are in my main system. I recently sold Model 6 monoblocks (w/ batteries) that were in my second system.
I will make an added comment about the sound of the Coherence II and Cadence run from batteries, as I believe you expressed an interest in the sound of the Synergy IIi with batteries. The difference is subtle and it is not. The batteries do not lower the noise floor so much as they confer some kind of subtle "rightness" to the sound that is hard to describe. As I said, it is subtle, but over time, I came to find that I much prefer my system with the batteries engaged (or more accurately, the A/C line disconnected from the batteries, as the Rowland battery power supply that comes with the Coherence II / Cadence merely disconnects the A/C supply from the batteries when "full battery" operation is engaged -- at other times, the components still run from the batteries, but the A/C supply is connected to the batteries). In short, my guess is that the two components were voiced by Rowland in pure battery mode, as again, there's just something more right about the sound in pure battery mode. As for the noise level on the Coherence II, it is by far the lowest of any preamp I have owned and something that I find addictive -- I can hear an incredible amount of information that my other preamps (ARC LS-3 solid-state, Hovland, CAT Mk. III, Jadis DPL-2) obscured or buried. As I listen to a lot of chamber music and symphonic music whose accurate reproduction depends in part upon the ability of the components to permit the listener to "hear" the venue in which the performance takes place, I love this aspect of its sound.
My comments about the batteries apply only to the Rowland battery power supply, which is evidently still available for +/- $3,500, feeding the Coherence II and Cadence. As for how Cytocycle's retrofit of batteries to a Synergy IIi would sound, I leave that to him.