Ah! That's a much bigger question than you probably realise and the answer would take pages, be full of ifs and buts and put most readers to sleep...
Printable View
In the early 70s as a broadcasting engineer, one of the seniors stated that someone had written a treatise on the precise frequency response profile that an audio amp should have.
I cannot remember the precise nature of it, but it was along the lines of being flat to about 50k and then sloping off at so many dB per octave, and then being flat again etc. It was very precisely detailed, and seemed odd at the time.
Some may but very unlikely generally... Naim stuff is very bandwidth limited for example...
The whole matter of bandwidth and negative feedback (they are intrinsically linked) and the implications of it, the reasons for it, its effect on stability, squarewave response, step response, settling time, changing the predominance of odd/even distortion harmonics etc etc is one of the most important issues in hi fi and has HUGE effect on the sound we hear even at low frequencies.... It would therefore be of zero interest to audiophiles :D
Extend the bandwidth to 250kHz and you can have a free AM tuner to listen to Radio 4 on long wave.
I made a power amp a few years ago which had a very poor bandwidth compared to what is possible - but it sounded fantastic! Unfortunately, it had a tendency to blow up :doh:
I've been meaning to revisit that project but haven't got round to it.
Anyway, the point is this: restricted bandwidth (though still beyond 20kHz) certainly didn't seem to have a negative impact on sound quality.