g_u_e_s_t:
if you just need a spectrum analyzer, "spectrum lab" is freeware, and ive been very happy with it. it can take in external audio from a soundcard, or work on saved wav files.
Thank you for your answer. May I ask if spectrum lab can be used to measure audio SNR? Or even better, harmonics and intermodulation distortion? I went to the website but could not find an answer.