Classe DR-15 amplifier compared to Classe Dr-9

Sorry for the late reply. I was using one Dr-15 to drive Apogee Stages and found the resulting sound slow and sluggish. I was also using a passive preamp so there may have been an impedence issue. Buying a second DR-15 resulted in a faster sound and more true to life. I experimented with short low capacitance cables and this also improved matters. I'm at the stage now where I'm satisfied.

The thread is from quite some time ago, but adding some input for those who arrived here through an internet search looking to research or purchase a DR-15 or DR-9. 

Adjectives such as "speed" and "fast" when discussing amplifiers, speakers, or cables seems to really be about how well a system accurately captures attack and decay:  the key stroke on a piano or the hit of a drum have an attack at the strike and a decay in the sustain -- an audio instrument that accurately manages these attributes is one that doesn't turn muddy, muffled, or unfocused at these sonic junctures.  In other words, an amplifier should have enough power to expand and contract the speaker fast enough to capture each beat of a drum solo; yet, the speaker needs to be fast enough to accept these changing demands from the amplifier and respond accordingly.

When all goes well, amplifier, speakers, cabling, even a stylus should all together have enough synergy and balance to maintain the integrity of the original instruments in play.

That’s a good way to put it.