High Sensitvity = good transient response ?

Thanks for honoring my posts, TWL as I honor yours the same. I have many reasons to believe you and probably I should give myself another chance to listen SET/Lowther but did you try to A/B your SET amp with more powerfull amplifier despite having Lowthers 100dB/W/m?

The ultimate tube electronics for me were always Manley and I had a chance to listen to Manley SET amps with Coincident Eclipce. I loved the sound but than I swiched for integrated EveAnna's 50W/ch amp and enjoyed much more.

As Sean stated that everything depends on funds invested into the product and almost every design can succeed in the right combination and it's realy fun for us to find our own equilibrium in funds vs. performance.

Marakanetz, perhaps you just prefer the sound of push-pull amps better than SET's. There is nothing inherently wrong with push-pull amps, and they have more power to kick the bass a little harder. My little Berning amp is actually a push-pull, using 6SN7 preamp tubes for outputs, and maybe that is why I don't feel that the bass is lacking like you say the single-endeds are. Whatever the reason, this little MicroZOTL kicks some booty on the bottom end. Really tight too.

Twl, about the 40 Hz rating. I've heard Brentworth single driver with Waytec SET (20 Hz rated) and the bass was disappointing.
Am I missing something because, take B&W Nautilus 804's for example,are rated at about 40 Hz but they seem to have more weight than the 20 Hz rated single driver? Is this a dynamics issue?

Cdc, the physics of speaker and driver design basically dictate that if you're attempting to reproduce (almost) the whole frequency range with just one driven element, you're going to have to give something up. It could be efficiency, dynamic range, extended bandwidth, optimized dispersion, etc., or a combination of some of the above. The payoff is supposed to be in the quality of "seamlessness" or "coherence" that comes from not dividing up the amp signal, not using different driver types or materials, and not intoducing lobing or phase anomolies, as well as possibly making an easier electrical load without a crossover for a low-powered amp to drive. In your above example, I'm assuming that the amps were also different, which would have something to do with what you heard (as would the rooms and setups), but yes, it's quite possible that a conventional multi-way speaker could exhibit superior bass dynamics. (BTW, what are the tolerances and conditions given [-3dB down or -6dB down? Anechoic, nearfield or in-room?] for the bass frequency response ratings you mention? If they're not the same, then you can't compare the ratings directly.)

I just checked out the Brentworth line on the web, and it seems interesting. Their specs on the top line model show a response of 15Hz-20kHZ within 3db. I find this a little hard to swallow, but they claim it. Seems they have a proprietary loading technique that supposedly allows this to happen. I've never heard them. If they sounded weak in the bass, that would be understandable, as I strongly suspect their figures. However, their idea could be a jumping off point for others to work with, and produce lower bass out of a single way system. The main question is: how do they sound in the rest of the spectrum? If they are no good there, then the bass is of little use. If they are great, then maybe I need to consider them for my system. About the comparison with the B&W's, the B&W's are a well made speaker that conservatively rates their systems, and may actually produce lower bass than their rating, in your room. In any rate, they are a good speaker, and I don't know if the Brentworths are good or not. It is notable that some single driver speaker mfr. is claiming to be able to get that kind of bass response, though. If you can tell us a little more about your impressions of the Brentworths, that would be very helpful.