Ok, I know that this forum is a few years old now but I am currently in a very similar predicament and looking to upgrade a pair of Monolith III speakers. I called Parts express and gave them the parameters of the ACI SV12 and they recommended the Dayton Audio Rss31515HF-4. Either @timlub @georgehifi are you guys willing to look over that Dayton driver to see if it would be an appropriate 2022 replacement? I do not have nearly the experience or the measuring tools to know/ understand the most important similarities. I know the frequency response is higher, but the parts express guys said it would drop a little after the break-in. I love these Monoliths and if there is a way to make their song sweeter I am willing to do it! Lastly, if these will work (or another recommendation as I am open to them) what would I need to do to make for the best compatibility? Lastly, I am personally using the active IIIx crossover from ML, and plan to continue to unless otherwise advised! Thank you all for this great forum as hit has helped pass worries regarding these aging gems!!
