What is a "Current Dumping amp??".. and Pros/Cons

Quad Audio's 909 amp uses a "current dumping" design. What exactly is the advantage or disadvantage of such a design?? The TAS reviewof the amp in issue #207 claimed that this might not be the amp for buyers,looking for deep or tight bass.

I have seen several of these amps on sale over the last year. I wonder the trend says this is just another soft sounding British amp with below average dynamics

Will greatly appreciate an explanation of this design principle, and any comments about the Quad 909's sound quality. BTW, over the years, I have read that high current amps usually have deep bass and very good bass control. I owned a Aragon 4004 MKII about 25 years which proved that issue in spades. Thanks
I'd be careful not to tie the overall sound of a component to one aspect of it's design.
here is a very good article (technical tho' I MUST warn you!!) on "current dumping":

please read - it should educate you sufficiently.....
The late 70s/early 80s dogma (as advertised) was that 'When Z1Z3=Z2Z4 something magical happens'. Or something like that, knowing that about everbody reading that copy had no idea what they were talking about. Although Quad was in the day very old school, they were not above advertising BS.

Quad power amps traditionally have pretty good design, but with (especially) their later solid state ones, crapola parts.And a small cottage industry evolved improving the quality of the 405 components without changing any of the design.
Isn't this similar to Threshold's Stasis application?
The article posted here (http://www.richardbrice.net/curdump.htm) is great and although I barely understand it, it's exactly the style of technical writing we need more of.
Thanks to all who have responded so far, especially BW supplied the technical article which is dense. However, I think we can understand enough, that Quad has been resting on its laurels too long. Their speakers over the years have offered great sound, but at too a high price, and required demanding set-up parameters and almost monster amps to drive them. With all due respect to Quad's founders and designers I think the company has seen its day.