You are precisely correct. The rep I talked with was pleasant enough and put up with my call-backs due to the fact that the ESP-950 was originally excluded from the sale.
On a more progressive note, I have been playing around with using my Valhalla 2 tube amp as a preamp for the E-90 energizer. The amp is designed with pre-outs so I'm using it as designed. I have never heard much about using a preamp with the E90 to boost performance, but I quite like the results. Even with the added gain, the noise floor is still very black (the V2 is VERY clean). To my ears the improvements are found in better dynamics, faster impulse response, better three-dimensionality and a subtle tube-smoothness.
Anyone else care to give using a preamp a try? There is virtually NO information anywhere regarding this kind of setup, so we are indeed the pioneers...