New to Magnepan, a volume question

Hello, new to Audiogon and Magnepan both.  I just acquired a pair of used MMG's and I'm really enjoying them, especially on certain types of music; acoustic jazz, vocal, and small to mid scale classical.  My problem with them is that I run out of volume knob with my current set up.  It is:  Schitt Saga preamp and Adcom GFA-555 amp.  The Saga is basically a passive preamp, it doesn't add any gain to the signal, and though I love the sound, full volume with this pairing gets me to just below an average listening level, no where to go when I want to push the envelope.  Will I get to higher SPL's using the passive with more wattage as long as the amp is a high current design?  The amps I'm considering are McCormick DNA-500, Bryston 7B ST or SST, and Bel Canto REF600 or REF1000 if I can find them.  I'm looking to build a better power amp foundation for the system of the future, as I can see now I may very well be heading toward larger Magnepans or electrostatic speakers in time.  I have a other preamps that will add gain, but they don't sound as good as the Schitt, and do push the Adcom to flashing lights when I get closer to where I want to be volume-wise.  Looks to me like the Adcom, as much as I have loved it, doesn't cut the mustard with 4 ohm loads.  I have heard that Bryston is a natural match for Magnepans, and also the they sound somewhat dull or flat.  Good reviews from users for the McCormick, and yes and no about class D amps (the Bel Cantos) with Magnepans.  I admit, I'm all at sea...  Any advice appreciated.