I personally find that amps with a usable bandwidth out to 150 KHz hit a sweet spot for speed, clarity, and transparency without opening up the can of worms that ultra-wide bandwidth introduces nor the too-sweet, closed-in sound of amps that just make it out to 20KHz.
Amps linear to 150 KHz (and I'm simply relating my personal experience from preference--I've owned around 20 amps over the last 40 years) have a combination of body and warmth, plus transparency and clarity that I like. Although few of us hear *frequencies* beyond 20Khz, I suspect all of us can hear the difference that the wider bandwidth confers on square wave *rise time* in regard to clarity and transparency that accompanies a bandwidth of 150 KHz and beyond.
Amps with ultra-wide bandwidth have an unmistakably stunning clarity, but are sometimes accompanied by over-ring and treble brightness at the expense of warmth and body, both musical values. And sometimes an ultra-wide bandwidth design can run into an oscillation problem with the speaker interface. It's my understanding that this is why MIT designed a special network for their speaker cables to prevent oscillation in their collaborative audio show system with electronics from ultra-bandwidth Spectral and speakers by Hales.
Amps linear to 150 KHz (and I'm simply relating my personal experience from preference--I've owned around 20 amps over the last 40 years) have a combination of body and warmth, plus transparency and clarity that I like. Although few of us hear *frequencies* beyond 20Khz, I suspect all of us can hear the difference that the wider bandwidth confers on square wave *rise time* in regard to clarity and transparency that accompanies a bandwidth of 150 KHz and beyond.
Amps with ultra-wide bandwidth have an unmistakably stunning clarity, but are sometimes accompanied by over-ring and treble brightness at the expense of warmth and body, both musical values. And sometimes an ultra-wide bandwidth design can run into an oscillation problem with the speaker interface. It's my understanding that this is why MIT designed a special network for their speaker cables to prevent oscillation in their collaborative audio show system with electronics from ultra-bandwidth Spectral and speakers by Hales.