My system consists of harmon kardon AVR235, Infinity Alpha 50's and Velodyne cht12 as mentioned. Now at -40 to -25 volume, sounds great with a lot of hit coming from the sub. (Almost too much at times) However once I get in the area of -24 and upper volume the sub just seems to start tapering out with the infinity towers coming to life with more and more volume in this range. Is this a problem with the receiver not having enough wattage at that point, I would assume a receiver doesn't make any difference, as it is hooked up in the preamp out and the subwoofer amp is powering all the bass.
Maybe i'm just trying to get concert sound out of system that's to small.
Turn the sub volume up when you hit -25, try not to go above 60% if you can avoid it. If that does not help set your 50's to "small", and adjust the low pass x-over to 120.