Most of what I was going to say has already been said here, mostly by @georgehifi. I do a lot of audio electronics, I use a QA401 for measurements (it's truly incredible value for money when you compare it to the other stuff out there) and an uncalibrated, analogue 100MHz Tektronix to 'see' the signal... usually square wave testing for oscillation which I find much easier on an analogue scope. It's worth remembering that although we can't hear higher than 20kHz, an amplifier can oscillate at any frequency in it's bandwidth so high resolution is a must.
I've used digital scopes which were useful at the time for the FFT but I don't need that now I have the QA401... if you set it up right you can measure distortion down to about 0.0001% along with all the other measurements you'd expect to run on an amp. Other than a 4 1/2 count Fluke DMM i could get by without any other measurement tools.
I've used digital scopes which were useful at the time for the FFT but I don't need that now I have the QA401... if you set it up right you can measure distortion down to about 0.0001% along with all the other measurements you'd expect to run on an amp. Other than a 4 1/2 count Fluke DMM i could get by without any other measurement tools.