[linux-audio-dev] audio spectrometer

Hi! The aim is to make measurement mini-laboratory, in particular, to measure distortions of audio amplifier. Using JACK, I can route line ins/outs, find clean sine signal and get amplified one, and then route last to... Well, the questions are: - are there some graphical FFT frontend to see signal harmonics? - has anybody success experience here? - are there some caveats and traps in such measurement? I have 24/96 card (Terrateck Aureon 7.1) with (as I think :-) good DAC/ADC. So, I hope, measurements may be done at least for few first harmonics. P.S. Have tried LAU list without any response :-( Thanks! Andrew