After copious research and searching, I finally scored a BX63 without giving up my right arm. I have been using a new manufacture Ashly 1001 crossover with decent results but as many of you know, it's not sloped per JBL specifications and lacks the 6db hump at 26hz. Wow, what a difference. I also moved my B380 from between and to the left of my mains to the left wall of my space slightly rear of center. That move was made with the Ashly crossover still in-line and there was an improvement felt. Adding the BX63 feels like a larger improvement. I also really like the bypass switch. I am running the B380 with a pair of L220's and sometimes it's nice to hear those boys full range. Following JBL's phasing instructions proved more difficult than it initially seemed. One is supposed to place the crossover in bypass, select some program material with a solid base line and slowly increase the BX63 level while putting the unit in and out of bypass until base levels are uniform with the unit in bypass and out of bypass. Then switch phasing and see if the bass gets louder or softer, louder being in correct phase. I have the ability to turn off my mains via a Bryston switch box (also a nice new addition) because I for some reason love A-Bing my speakers... and even with the mains off, I have a hard time hearing the difference when switching from normal and inverted phasing. How subtle is the difference? Everything sounds great but I thought the phasing change would be more obvious. Should I worry? Or just leave it be.