I agree with many of the participants here. If you really like the ML sound, then stick with ML speakers and upgrade to higher level ML speakers. I was going to suggest upgrading to Request speakers with new panels. However, one poster suggested summit speakers. I have heard the request and summit and if you can find them used, grab them if they are in you budget. Quite honestly, the mid bass and upper levels on upper level ML speakers are amazing. Now that they have eliminated the bass/mid bass crossover issues, those upper level ML speaker are really nice. With clean electronics, you will fly and with your Audio Research electronics, you are there. I bi amped with AR mono block tube amps on my panels of my Monolith IIIXs and Mark Levinson ML3 on the base drivers. Wow! Then I got my hands on an excellent Mark Levinson 23.5 and use it on my upper panels. I've said it before, but the ML 23.5 is still one of the best amps ever. But I will stick with my Martin Logan speakers. I got new panels, new electronic crossover replacing my passive one and new power supplies from Martin Logan and again, wow! And I routinely go to my favorite store (Stereo Design in San Diego) and listen to the best. Mine is pretty good. Stick with ML if you like the ML sound and upgrade to Request or Summit.
Enjoy
Enjoy