Not including the 6" Fostex for comparison, but focusing on the FE103En 4" drivers in the P1000 BH folded horn enclosures from Madisound (dark brown) and the Blumenstein Orca using the 3" Fe83En. I'll take measurements a bit later. I might throw in the 4.5" Fostex drivers in some larger cabinets this weekend if I get a chance. The Flugelhorn flatpacks for the 4.5" drivers I ordered last year don't seem to be going anywhere - some story about the CNC software crashing. I guess I'll write that off on my taxes. Quick impressions: The P1000 likes to be placed further back to the wall to get low end reinforcement compared than the Orcas. This is not to say that the PH1000 are less bassy. The P1000 actually has better bass extension, albeit at a lower volume in relation to the mids. The P1000 mids have that typical full range midrange shout. The Orcas have less of that shout, but are also more rolled in the bass and highs. Neither have perfect tonality. With an EQ circuit or DEQ, the PH1000 would definitely have more potential because of better extension .... The Orcas sound more congested and closed in. The difference is significant. Not really surprising since the Orca uses a much smaller 3" driver in a box (the box is ported). The P1000 4" driver just has an easier time pushing air, and the back loaded horn allows the driver to breath more - more lively, more open, soundstage is deeper past the window. None of these drivers can be considered high efficiency. Moderate efficiency yes. High efficiency no. They do demand the highest quality amplification. Don't bother unless you have epic amps and sources. You will not understand their "magic" by using say a pedestrian Parasound P5 and A23 combo. That being said, most people are better off with an KEF LS50 or Q series speaker at around the same price or less. Although it should be mentioned that the complete P1000 kit is currently $235 at Madisound.