I too find the R2R-11 not the best solution for the Atticus.Of the three amping options I currently have on my desk the R2R-11 has the least amount of slam and aggression.To my ears its just too warm when im listening to older recordings e.g. blues,classic rock,NWOBHM...pretty much 90% of what I listen to.
In my attempt to find a great amp for the Atticus I ended up ordering a Monster Eleven Glenn amp(AKA M.E.G.A.) I will have Hansotek on speed dial so he can try and prevent me from blowing up my house.