LAConvolver for Mac

From Lernvall Audio:

LAConvolver is an Audio Units plug-in for convolving the audio stream with an impulse response stored in an audio file. LAConvolver is free but donations will certainly encourage further development.
Features:

• Support for 1 to 128 audio channels, all with independent impulse responses
• Most audio file formats supported for the impulse responses
• Automatic sample rate conversion of impulse responses if needed
• Low latency, determined by number of frames per slice
• Sensing of silence in impulse responses gives low CPU load for delay effects

Known issues:

• Universal but not optimized for Intel
• No support for raw PCM files

Performance:
The CPU-load is dependent on the number of frames per slice, larger slices give lower CPU-load. On an iBook G4 800 MHz with a sample rate of 44,100 Hz and 4,096 frames per slice the CPU-load is about 3% per second of impulse response.