Interesting posts - the filter sounds like an interesting tweak. Generally I agree with Akhilesh - the route I took was to get a reasonably priced amp that produces a good pure couple of watts along with a very sensitive speaker to compensate for the lack of power in the amp. I spoke to Steve Deckert about speaker matching with his amp before I got the Zen and at that time (about a year ago) he told me the 206E was the best match he'd heard (he may have backed off that since then, I'm not sure); he also likes the Lowthers. On a related note, If memory serves, I think Steve built some kind of filter for Lowthers (I think he calls it the Lowther Gizmo) but more to reduce the mid-high "bloom" some complain of on the Lowthers. I don't think Martin is all alone out there on his branch, and to me the filter tweak is more "zen-like" than adding drivers. If there was a filter to "supplement" the bass on the Fostex I would definitely try it out.By the way, do you have to have a filter (or a crossover) if you use a driver that only produces a certain range of frequency? For example, it seems like if you use a super-tweeter that only goes down to 10K-15K it, or a sub that only gets up to 60Hz-80Hz, could you play all three drivers "full range" without a crossover? Would this require a separate amp for each driver? Would that still introduce phase inconsistency problems due to the drivers not firing at the same time (I guess it would)? I don't know much about this stuff, so if I am being an idiot just ignore me. Phil.