I started with 4 buttkicker LFE's in 2009. Thought they were great. But sometimes they bottom out and make a horrible noise. For that you have to turn them down until that *never* happens. This, in turn causes the bottoming out point in a single movie to be your limit of where you can run them. (I used transformers 2 intro as a test that always bottomed them).
Later, I discovered earthquake qb10's. These were a little better than the buttkickers in that they were slightly faster and if you like the transducers with music, they're much quieter than the buttkickers. They also never bottom out - never. Unfortunately, these are $550 a piece. Ouch. I bought 4
While these were quieter and more musical than the buttkickers, they still made a little bit of noise at very low volume music. So...next up the MQB-1.
For whatever reason tried out an earthquake MQB-1 from amazon. They're $150 shipped prime. I figured I had nothing to lose. I was quite shocked that these were by far the best shakers I've ever had. First, they're dead silent. You never, ever hear any sound. I can play music at a very low volume and still get a pretty satisfying shake from these without having to have them cranked up. At these volumes the buttkickers would not move at all. I also found that these things disappear into the subwoofer so well that you dont realize they're shakers instead you just think you moved your subwoofer into the couch. They're just as aggressive as the buttkickers at high volume if you have attached them to your furniture using the included bracket (this is the way you want to run any shaker anyway). The reason these things are so much better for music is that they feel faster. Instant. You don't realize it until you do a comparison but the buttkickers are a little sloppy or slow comparatively. I cant recommend the earthquake MQB-1 enough to anyone that wants shakers. I bolted 4 of mine to each of the 4 main seats using the bracket that comes with them.
Yea, next is the amp. The buttkicker BKA1000 is by far the best amp for shakers I've ever used. I've tried crowns, ep4000 (which I love for my subs), inuke amps. There's just something about the buttkicker amp that drives shakers better. It's almost like the amp is slightly boosted at the frequency where you want your shakers to perform. Unfortunately, these amps are no longer available and haven't been for a few years. I bought 2 extras to store in case of emergency. Unfortunately, these amps are known to go up in smoke so maybe that's why they're no longer available.
Of all the substitutes, the best I've found was an inuke1000dsp (or 3000dsp), which if you enable the DSP and give a little boost around 20 hz it does pretty well for shakers. I could probably be happy enough with that setup as a last resort. If you go this route, you'll want to also buy a $70 cleanbox pro (amazon prime) to bring the input levels up. The inuke amp is unusually sensitive to the lower voltage provided by unbalanced home audio outputs. With this cleanbox pro, you'll have tons of power for your shakers. The inuke1000dsp can run 4 of them no problem.
In summary, I'd go with earthquake MQB-1 instead of buttkicker. Not only do you save $100 each, you get much better performance especially in music. Worst case you can buy from amazon prime and return and buy a buttkicker instead if you're not convinced. If you cant find a used BKA1000 amp, I'd grab an inuke1000dsp and cleanbox pro and call it good. Oh one last thing. I should note that the regular price for the MQB-1's is $300 a piece which is more expensive than the buttkickers. But amazon prime seems to *always* have them at $154 or so prime.