Stehno: J. Peter Moncrieff of IAR showed why one cdp sounds different from the next. He did this many, many years ago to specifically demonstrate that some "golden eared reviewers" really were hearing differences and not imagining things. This is one of the reasons that i like Peter i.e. he not only gives you aural impressions of the gear but also takes the time to actually measure and explain why gear has the sonic personality that it does.
By playing the same identical note on one player and measuring / charting the response and repeating the same procedure on another player, it became quite visible on a waveform that one player had better transient response ( faster rise and fall times, which are what gives us the "attack and decay" characteristics that you mention ), greater dynamic range ( higher positive and negative peaks), lower noise floor i.e. "increased inter-transient silence" ( reduced ringing for greater silence between notes / increased separation of notes), etc...
As you can see, all of these factors could contribute to a very different presentation in terms of "slam", timing, pace, etc... even when using identical source material. I find it both amusing and appalling that a magazine with the stature of TAS could not understand / know why such things occur.
Bear: Your comments intrigue me regarding power supply sag. Does this take place in designs that are fully regulated ? Do you know of any designs that regulate the output section ?
Bob Crump: While i can agree with your comments in theory, who is to say that all music / speaker systems can get by with less than 30 - 40 watts in Class A ? While you did specifically state 89 dB speakers, who is to say how big of a room one has or how loud that they like to listen to specific types of music ? What if the speakers being used were of a low impedance design ? That in itself would change the operational area of the amp in terms of switching from A to AB. Sean
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