I want to build an Oscilloscope with an Arduino. The main scope for the system is to "see" audio signals, so the highest frequency would be ~10 kHz. With those signals, each sample shoudl be taken each 3 us.
I've never used the Due, but I think that should be possible. What are you using for a display?
You'll need to bias the input (to allow for the negative half of the waveform) and you'll probably need to amplify and/or attenuate the signal to keep it within 3.3V P-P. And, you'll need to protect the input from negative voltages and voltage greater than +3.3V.
I want to confirm Arduino Due as a good platform to implement the Oscilloscope.
Probably not for a good oscilloscope. With enough add-on electronics (an instrumentation amplifier, fast ADC, more memory, etc.) you could probably build a good 'scope around a Due (or any microprocessor/microcontoller)... But, it's not an easy thing to build and I wouldn't try.
Somewhere on this forum I've posted interrupt-driven code for sampling the ADC
(and driving the DAC too, for what its worth). I forget the subject line, but a forum
search might throw it up.