Excellent selection! As an owner of a Concentra II, bought used here on 'gon not long ago, I rush to welcome you to the JRDG fan club.
My experiences may not be useful, given the difference in the two designs and power supplies. However:
I've found the Concentra II to be so VERY solid/stable that it is decidedly more "indifferent" to cabling changes than other gear I use in other systems. In that respect, switching among cables with the Rowland has been a complete surprise, compared to the other amps and preamps I've used over the years. While you can probably "kill" the glory of the Rowland sound w/ an overly dark or dull cable match, you will probably have a far larger range of decent choices than with other amps/preamps.
The C II has worked very well with Shunyata Phoenix SC, paired with rca ICs. I tried the Phoenix first, and found no need to look on.
As to interconnects, Transparent ICs were just fine, but I moved on. The Ridge Street's Poiemas were better (in MY system), both rca b/c the cdp and tuner in the C II set-up are only single-ended. I've also happily plugged in Ridge St's MSE, rca, w/ the Concentra II.
Some systems won't mate well with silver wires, as you know. I suspect you'd want to tread cautiously, if you are still using the Piegas. I'm running Aerials in the system w/ the Concentra II.
PLEASE let us know how you like the Concerto integrated, and what wire you ultimately pick.
