Are you guys using unix/linux ?
I did a simple test with the venerable 'sox' and its very quick - it should
work fine on stdin/stdout as well for streaming audio.
This takes out 60,120&some 240Hz from a 30min snippet.
Works really well - almost all hum is gone!
> time sox -V PANC-Feb-22-05-0000.wav out.wav bandreject 120 120
sox: Detected file format type: wav
sox: Chunk fmt
sox: Chunk data
sox: Reading Wave file: Microsoft PCM format, 1 channel, 22050 samp/sec
sox: 44100 byte/sec, 2 block align, 16 bits/samp, 79490304 data bytes
sox: Input file PANC-Feb-22-05-0000.wav: using sample rate 22050
size shorts, encoding signed (2's complement), 1 channel
sox: Input file PANC-Feb-22-05-0000.wav: comment "PANC-Feb-22-05-0000.wav"
sox: Writing Wave file: Microsoft PCM format, 1 channel, 22050 samp/sec
sox: 44100 byte/sec, 2 block align, 16 bits/samp
sox: Output file out.wav: using sample rate 22050
size shorts, encoding signed (2's complement), 1 channel
sox: Output file: comment "PANC-Feb-22-05-0000.wav"
sox: Finished writing Wave file, 79490304 data bytes 39745152 samples
2.390u 0.940s 0:03.91 85.1% 0+0k 0+0io 197pf+0w