I have just been through the same ordeal with similar equipment. My solution was to add an anolog pre with unity gain surround loop and use my HT receiver as pre/pro for movies and multi channel. Made a huge difference with 2-channel. From the equipment you have listed it appears that your receiver has main ins/pre outs for all channels. If your receiver has the processing features you want I would reccommend keeping it for now and getting a good preamp with the surround loop. As you stated good pre/pro's cost an arm and leg and still may not do 2-channel as well as a preamp that costs a fraction of the price. Additionally a 2-analog preamp will not be obsolete with the next generation of dolby, dts or whatever and you can just replace your receiver with another with the newer features.
Anyway, just my rationalization.
Anyway, just my rationalization.