You can make boxes, but not electronics? Maybe the 604 is for you ...

Woohoo!

I have a pair in 6 ft boxes tuned with dual ports to 49 hz or so. They sound great and yes I agree about the caps. I installed some Jupiter beeswax and wow what an improvement. 
They do some things incredibly well and others less so. 
Dual subs took them to the next level, as they show less bass than a decent monitor. But man, what they do well is voice, horns, dynamics and soundstage. 

+1 for the 604's!