I just spent some time with the Sadowsky cabs and my 750 earlier this week! With one SA410, it is pretty much exactly what you would expect - thick, full, punchy, chewy rocking goodness! Because the cones were designed to work with a tube output stage (SA200), they are almost "too tight" when used with a quality SS amp. As a result, the low end when used with a SS amp can take a little boost, but this is a minor thing and easily accomplished. The DB 750 has a different tone and, perhaps more significant, a different "presentation" than the SA200, but this is certainly a very good combination. Inteterestingly, when you add the SA210 to the SA410 with the 750, you notice not only an increase in the high end clarity and expansiveness, but also significantly more low end. With the SA200, the benefits of adding the SA210 are more focused in the upper mids and high end (and man, it makes a wonderful difference, here, with the SA200!), so I was somewhat surprised to see how much it affected the lows with the 750. My guess is that going from the 4 ohm load to a 2.67 ohm load was a major factor, since this will push the SS output section of the 750 to crank out more power, and with the tube output section of the SA200, the output remains roughly the same. More factors may also be in play, but I haven't really investigated this.
Tom.