You forgot to mention, that the dart dislodged the $60k 911mk3 monos from your system :)911mk3 has a very low input impedance, is it POSSIBLE a preamp impedance mis-match problem? Did you use the Dartzeel 18NS?
TAD CR-1's is 86db, I'm surprise Dartzeel 108 can drive them as well as the 911Mk3 monos.