I have the 7125 and the 7500. The 7125 is my everyday, use it all the time, machine. I drive some Magnepans with the 7500 because they are power hogs. Can your mains be bi-amped? If so, I would suggest the 7125 and you can use two channels for each of the mains. Recognize that 200 watts output gets you +2 db SPL over the 125 watts from the 7125. You don't sound like you need balanced outputs so save the $$$ and try out the 7125. Your speakers are 89 db efficient and the 7125 will drive them to extreme levels near 110 db vice the 7500 which will go to 112 db. If you can bi-amp, then you can have as much power as you will ever need to the mains and much more power to the rest of the system.