At therisk of being contentious: Aggressive treble is more a sign of poor clocking than a design fault of delta sigma dacs compared to r2r dacs. Even highend dacs benefit from reclocking with Mutec, Cybershaft, Antelope, sotm et al. There is no superiority in r2r dacs, they tend to be more euphonic but sometimes less resolving. YMMV
Downside to R2R Ladder DACs?
A sales person I generally trust told me to steer clear of used R2R DACs, since their reliance on high precision resistors causes them to sound best when new, and degrade fairly quickly. It seems reasonable; have others had any experience with this?