a dilemma for cartridge/phono stage combination

Apparently, your major responder, Robjerman, is under the impression that your current phono section is a type built for "high output" cartridges, most typically a moving magnet type.  However, if I read your own posts correctly, you did have enough gain for your high output MC Benz cartridge that is now broken.  Such "high output moving coil" cartridges typically put out 1-2mV, whereas a typical MM cartridge is more like 4-5mV in output.  Probably the reason your Monster cartridge sounds dull and lifeless is because the gain of your phono stage is not sufficient to bring it to life.  Do you find that your volume control is near to its wide open position, when you listen to the Monster?  If so, then you do lack the gain necessary for a low output MC.  In which case, you need either a SUT or a new phono stage with higher gain, or both if you also want an improvement in overall SQ.  A "Step-UP Transformer" or SUT is a transformer that increases the signal voltage output of a low output cartridge, to make it suitable for driving a low gain phono stage such as yours.  The SUT adds no real "gain" per se, but it converts current to voltage; most low output MC cartridges make a decent amount of current but only very low signal voltage.  Your MM phono stage is voltage-driven, so it benefits from the SUT placed in between the output of the tonearm and the input of the phono stage.  There is more to it, if you want to know more.