McIntosh buffs: Can anyone tell me what the.....

Digital Dynamic Amplifier 7*** series was all about in the late eighties/early nineties? Examples include the 7150, 7270, 7300. What is "digital" about them and what makes them deserve a name different than the before and after series?
I'm not sure, but I have 2 MC 7300's, and 1 MC 2205. I've compared them, and the 7300 has much better bass control and a bit more "authority". Both are sweet and tubey in the mids. They're hooked up to 6 Klipsch Cornwalls, and the 2205 powers the big award winning Klipsch center channel. The 2205 is about 27 years old, and the 7300 about 6 I think. Don't know if this helps. You may be looking for the technical and accurate answer. Have you tried Roger's Sundial site? This gent know all there is about Mac as a former engineer.
Thanks for the info. I know Roger's site very well and have tried to email O'Brian but got no response.
E-mail Stephen Sank, I would be VERY surprised if he didn't know.
The mid 80's 7xxx series was essentially just an update of the second generation ss amps(2125, 2205, 2255, etc.). At that time, simply having ample dynamic headroom was considered to qualify an amp as "digital ready", which was the only intention of the moniker. Now, such a label is something of a negative, in these days of analog revival & SET amps, and all that. The 7xxx series & the previous 2nd generation amps, in my opinion(I was selling both series when they were current) had very little to complain about in terms of tonal balance, transient response & other technical parameters. However, they were simply not very musically involving. The first generation ss Macs(2505, 2105, 2300, etc.) were far more musical, and are still among my favorite ss amps overall. I don't think Mac got back to this kind of quality until they brought out the MC1000 & MC500 amps. These, of course, were far more money than even a mint condition, new-in-box old MC2300 would fetch on ebay, and for the price difference, I'll take the old amps.