I have had my M80v4 HP's for over six months now and I am very pleased with them and the low end performance. I find the bass to be tight and accurate and they go lower and produce low frequencies much better than my old speakers. And I find them to be very neutral and easy to listen to at all volume levels. I won't have purchased them if they didn't offer the HP drivers.
I believe they did need a break-in period, which had much to do with me getting used to listen to them after listing to the same Infinity's they replaced for over 20 years.
My new 120 watt Pioneer A/V receiver drives them nicely and they can reach a volume where ear tells my brain that the music is too loud.
