Hi, the first thing I'd suggest is to talk to your friend about letting you hook up the Triple 12s in your room so you can more easily make the decision. On paper, there's a huge increase in efficiency going with the JTRs, over 11db so lots of get up and go with even receiver power. You'll probably inevitably start listening louder not necessarily because you can but because it won't sound like you're at the levels you are. -17.5 MV will be a mere blip on the radar. I had Triple 12s and liked them and in general always prefer dynamic speakers for the headroom. I want my own preference to be the limiting factor not my speakers or subs. Good luck!