After purchasing and installing Adam A7 studio monitors last year, I've felt my system lacked a bit of low bass. The A7s are extremely accurate and unforgiving until you get around 50Hz and then they really start to roll off (they're spec'ed down to 46Hz with a 3dB roll off). The newly acquired Adam Sub7 reaches down to 31Hz and really fills out the low end nicely. I still need to calibrate the sub, but early tests seem to indicate a frequency response a bit lower than 31Hz, perhaps down to 28Hz. Bypassing the sub7's 85Hz crossover and letting the A7s roll off naturally seems to provide the smoothest response so far, but I still have some experimenting to do.
Please excuse all the cords in the second photo - I was anxious to get things hooked up!