* the rapid charger is probably not the main problem on battery life issue. It took my slow charger over 10 hours to charge a pair of ultrafire, and the run time is 2 hour 50minutes, about the same as the rapid chargers.
Since you can use the unprotected cells in the battery bay, it is probably cheaper to just get one more pair of batteries.
* The amp is now pretty stable. It was quite warm for the first two days, I could feel it on both top and underside of the plastic case, which made me kind of worried because the +/- supply caps are right above the opamps and I think most of the heat came from teh opamp. High temperature is never a good thing for electrolytics. (though the UnitedChemicon PS caps are rated for 105C operation, so really there is no need to worry.) Now the case is only slightly warm, I think the burn-in of the opamp is nearly completed.
larry, the package will be sent back tomorrow afternoon. After receiving it, you probably still want to do two more days of burn in. It has about 60 hours on it right now, and according the AnalogDevice, BJT opamps need 70-100 hours to fully stablize. (I think the 8599's are BJT input, since the input impedance is quite low -- comparing to the FET input opamps it is).-- update: ok the 8599 is not BJT, it is still FET input, I got it mixed up with the 797
... anyway, more burn-in won't hurt
by the way, I have put the original parts (taken off the MKI board) in the package too, and two of the ultrafire protection boards, just in case you might need them for whatever reason. I am keeping one ultrafire pretectin board, I will see if I can come up with a protection/dummy cell so you can use the lithiums in your stock MKII.