A long time ago a friend of mine loaned me an old pinnacle sub that his father-in-law gave to him. He didn't have any use for it and it was just collecting dust in a closet so he said I could take it. This thing was relatively small, and I was most surprised by how heavy it was given its size. After getting it all hooked up it was obvious that the sub was of extremely high quality. at 1/3rd volume, it shook my whole house. I tried looking up anything I could find on the brand/model but couldn't find anything but the website for pinnaclespeakers.com, so I finally emailed them. In 2 days they got back to me with not only a reply but a congratulations. I guess my friend had loaned me a very old banged up (but still highly functional) digitalsub 600 (check out the specs, its impressive). At the time, it was their flagship sub and from the sound of it, I could see why. I'd not heard bass response that impressive (or loud) outside of a movie theater. Anyway, not wanting to rip my buddy off, I told him about the speaker he loaned me and he took it back. That was my first experience with pinnacle, so I was eager to jump on the sale. I ended up ordering the pinnacle mb8000.
It could be that I'm replacing an antiquated system - yamaha yht-750, but I've been really pleased with the sound. I was left with the impression that my old yamaha htr 5740 didn't have the juice to power them (I could turn the receiver all the way up with zero distortion) and it still sounded like it could take more. I ended up locating on onkyo 606 of some local classifieds for a STEAL, and the combination of both the 606 and the mb8000 has made me very happy.
there is some "slap happiness" to the sub. I consider this to be VERY common with smaller subs. It's a 300 w amp driving an 8 inch speaker. its very responsive, but yes, once you get to "room shaking" volumes there can be some distortion. I haven't owned a ton of equipment, but I've seen a LOT of smaller drivers that "thwonk" out when turned up too loud. I've also seen a lot of larger subs that sound pretty sloppy and muffled when loud. I think its all about tuning your gear properly for the listening environment you like. I found it can be minimized by turning down the volume on the amp (of the sub) until the point of clarity, turning down the EQ on your receiver, or maybe a combination of both. Setting up new amp + speakers can take time to fine tune to the way *I LIKE IT*. That being said I'm pleased with the results so far.