and i heard ad712 sounds ******... :wink:
in common ad712 seems to be a typical "to be replaced" opamp while the ne5532 is really some kind of low noise universal audio opamp.
if you wanna do an upgrade i would give a chance to MC3308/3309 single/dual opamps like gyraf (and rane) use a lot :grin: .
if you like the deep dark BB sound try opa227 (not as cheap i think) types and if you wanna stay with AD try definately the 797 (it's specs are really beyond good and evil).
...but read the datasheets and application notes carefully and take care of an appropriate psu...blablabla
sorry for ranting