Couple of options and my own 2c of opinions...If you generally like the maggies sound and think you may keep them..May I offer a few suggestions to get the most out of the stock MMG you have....
First...
read Peter Gunn's Magnestand site as mentioned above, AND the MUG site for as much info as you can. Email and talk to Peter for some very good info on the MMG..He really knows how good the MMG can be. MMG is a very good speaker, even stock, despite the size and natural comparisons made to the larger maggies. But larger Maggies are not always the answer, especially depending on your room size..( which would help us to know) BTW..Larger maggies are NOT MADE BETTER, just bigger, with more driver surface and different crossovers as well as adding the ribbon tweeter..all of which require their own set of requirements especially in power feed to them. Thus the semi-fallacy of having to get bigger maggies to "upgrade"..be careful about size here..it can ruin the experience if your not prepared to move mountains to accommodate them!.
A MG12 may fit the bill and sonicaly presents a picture with the musicality and generic soundscape of the MMG, but adds the better detail and clarity of the bigger 1.6, in a more room friendly size. I have owned the 1.6 a few times and find now the 12 matches my 19x22 room much better. The key( also for the MMG) is lots of room to breath off the front and side walls and proper room treatments to get the best of Maggies. Too many Maggies users try to stuff their speakers to fit in their small rooms or dont set them up to get the best from them and are quickly dissapointed..when all along there is superb sounding transducer that lies within...and just needs some proper placement and room attention. If you dont have sufficient room from the side wall to the speaker, you will find them a bit bright and thin sounding. I have 4ft to my side wall on one side and still needed to treat the wall with heavy sound absorbing material (carpet!) to smooth out the sound. Things like this make a huge difference with planers such as maggies.
Also, MYe stands while seemingly nice, can ruin the overall sound of the mids and highs and bring a bit of beaming of the sound at you. ( read the Magnestand site) You tend to lose the air and decay with them standing straight up.. I have yet to hear maggies( or anything for that matter...) sound better when you set them up with them tilted back and slight toe-in and spread apart at least 8-9 feet.
I completely agree with Magnestands recommendations on set up and rake, which is Magenepans positions as well.
of course, Gunned Maggies are a whole 'nother story and as Peter would say, they sound nothing like the factory sounding maggies. I have not heard them myself and have considered this, but am just not in a position financially to go this route.
Subs are a logical choice to try with MMg's..but make sure you investigate fully what subs work and those that may be too much or ill matched. Most REL subs with 10" driver size would be a good choice and driven of the speakon connects only for best sound. Many here have used REL's with great sucess.. No one has ever been shot for using a REL! You should also email and chat with Duke (Audiokenesis) about his "Swarm" subs which use multiple arrays of subs positioned about the room and incorporate smaller drivers for better integration.There's chat here and on the MUG site about his excellent subs that are made for speakers such as maggies and planers in general.
As for using the tweeter attenuators, they work at the expense of taking the life away from the upper mids and highs. Id throw them away and work on the room and placement..then use a very good cable to connect, the stock jumps are nothing special either and many find that a good aftermarket cable works better, especially if it matches your speaker cables, and lastly, if you still think you need one..try a sub.
All my own jaded opinions ;-)
