I'm thinking of dynamic impact on transients. It's really not that subtle, honest! An orchestral climax can include all instruments in all frequency ranges. Some equipment might emphasize the higher frequency portion of the sound more than the rest of the frequency spectrum when reproducing the transient. The result may be a crisper or sharper-sounding leading edge of the transient, which can sound exciting but ultimately can lack the weight of a transient reproduced evenly over the full frequency spectrum. An example I can think of was my early Krell SBP 64x DAC--when I had it upgraded years ago, the first thing that struck me was that orchestral climaxes had more weight than before and seemed less grating on my ears; Krell told me that the upgrade had smoothed out some distortion in the treble they had found, and that was the result. Another example I can think of is the difference between early Krell and Meitner amps in reproducing orchestral climaxes--the Krells had much more apparent high frequency energy than the Meitners. The KT90s in my amps had more of a high frequency emphasis than the KT88s, which seem to me to better balance the frequencies (that's also why I use Telefunken 12AU7s in my DAC instead of the Mullards supplied by Audio Logic). I think that if I listened more to rock music, I might prefer the KT90s in this regard, as they would emphasize rim shots, cymbal crashes and snares. Make any sense?
