hypoman is the first, and only, contributor to this thread to even mention an essential parameter relevant to almost every other suggestion: that the SPL meter must be properly "weighted." The meter elliotbnewcombjr actually provides a link to will be useless for measuring bass output: it is "A weighted," which does not register anything below 100 Hz. The vast majority of such inexpensive meters available on Amazon or eBay are "A weighted," like the one in that link, which are intended for measuring industrial noise levels, not music. I learned this the hard way: I acquired one of those "A weighted" meters, and was puzzled that the readings I got seemed impossibly low for the subjective loudness they presumably measured. A device that will allow you to switch between "A" and "C" weighting will dramatically reveal the difference. And since the OP is interested specifically in "how low" his speakers will go, none of the suggested meters in this thread will be of any use at all in determining this.
