One of my Mosconi One 120.4's has been showing its rear for months now and finally got fed up with it. It would work perfect and then out of nowhere go POP and then work fine for several more hours. Checked everything and tracked it down to the amp. I asked around and the clear winners for my needs were the Arc xdi and JL xd. I decided to pull both of my a/b 4ch amps out and replace them with a single 8ch amp. I still have one good 120.4 to use if the available power from the 800/8 isn't enough, but after hearing what this little guy can do it has enough to get crazy loud without falling on its face.
I'm running a 3-way front plus a sealed 10" sub. Sensitivity for all my speakers is what I would consider "standard". All of them 4 ohm and sub is a d2. I'm sending 75x6 to the fronts and 200x1 to the sub. The sub is in a box laying in the rear passenger floor of my Ram and firing over the tranny hump towards the drivers side. This makes the sub the closest speaker to me. I have the gain sensitivity set to "low" which tops out at 2v input with gains all the way down. My processor has 2v outputs so this works out perfect. It has settings to set it up just about any way you want. Read up on it if you haven't already. For those of you that think you need double the power for midbass and double again for sub, THINK AGAIN. Yes some systems require you to send more to the sub and midbass but in my setup I had to pull the midbass level down a couple clicks with the processor and even more on the sub. I used to think you needed crazy amounts of power to cut down on noise and distortion but now I've seen for myself that as long as you have a QUALITY amp you can get by with something that's rated for less than 100rms per channel.
Compared to the Mosconi One 120.4's the JL seems to have better control of the speakers and is also making the little nuances in the music pop out and be noticed more. I was a diehard a/b guy but now I know that fullrange d tech has come far enough that amp topology simply doesn't matter anymore as long as you avoid the turds in the punch bowl. I've spent enough time with this amp to know that it's a step above the Mosconi amps which were more "gentle" if that makes any sense. Best way I can describe the difference between the One series and xd series is the One series was like a big cushy granny car. The JL xd amps are more like a nimble sports car. Both have their place and I love big cushy cars but for articulation the sports car is where it's at. It's really cool being able to run the whole system with one amp. This 800/8 does a great job and don't see any benefit in throwing more power at my 7 speakers in my system that what it's giving them.
In closing I know I was all over the place in my review. I seem to do a lot better with answering questions than I do with giving speeches. I tend to ramble a lot when I'm not sure if I'm giving the info people are looking for. Big thanks to 1800collect for sending me a link to refurb JL amps from Creative Audio. I got an amp that retails at $699 for $489 shipped. And the way it looked and was packaged when I got it I would have thought it was brand new if I didn't know any better. Who knows, they might have sent me a brand new one for all I know. It came with a 90 day warranty through JL. I figure if an amp is gonna puke it's gonna do it in that 90 day period, but my luck it will be on day 91, lol. I think it will be OK though and if I get 3-4 good years out of it I'll be happy.