Hi Roland,
I have a recent model iMac and will be starting to play around with REW soon. I'll let you know if I can figure out what the problem is. Have you tried using Apple's own GarageBand recording application which is bundled with most Macs?
Another possibility might be a free software program (we like those!) called
Line-In which allows direct playthru from your input.
For reference, here are the stated specifications of the iMac's analog audio input/outputs. I believe they are the same as all other Macs, so there shouldn't be any model-specific limitation as far as I can see.
Quote:
Line input
The analog line input operates independently from all other audio input ports and is always available. The line input supports recording at bit depths of 16, 20, or 24 bits per sample and at sample rates of 44.1 kHz, 48 kHz, or 96 kHz. Audio recorded from the line input is presented as a stereo data stream. The line input gain can be adjusted from -16 dB to +30 dB.
During input of a 1 kHz, 1 VRMS (-3 dBFS) sine wave (44.1 kHz input sample rate, 24-bit sample depth, 0.0 dB input gain, no weighting) the audio line input has the following nominal specifications:
Jack type: 3.5 mm (1/8-inch) stereo
Maximum input voltage: 3 VRMS (+11.8 dBu)
Minimum voltage input for full scale output: 63 mVRMS (-21.5 dBu) at input gain = +30 dB
Input impedance: > 20 kilohm
Frequency response: 20 Hz to 20 kHz, +0.5 dB/-3 dB
Signal-to-noise ratio (SNR): >90 dB
Total harmonic distortion + noise (THD+N): <-85 dB (0.006%)
Channel separation: > 85 dB
Line/Headphone output
The headphone output is automatically selected for audio output if no external S/PDIF optical digital output device is detected. The headphone output supports a stereo data stream at bit depths of 16, 20, or 24 bits per sample and at sample rates of 44.1 kHz, 48 kHz, or 96 kHz. The headphone output volume can be adjusted from 0.0 dB to -64 dB.
During playback of a 1 kHz sine wave at -3 dBFS voltage level, 24-bit sample depth, 44.1 kHz output sample rate, 100 k load (unless otherwise specified) the audio output has the following nominal specifications:
Jack type: 3.5 mm (1/8-inch) stereo combo
Maximum output voltage: 1.6 VRMS (+6.3 dBu)
Output impedance: <24 ohms
Frequency response: 20 Hz to 20 kHz, +0.5 dB/-3 dB
Signal-to-noise ratio (SNR): >90 dB
Total harmonic distortion + noise (THD+N): <-80 dB (0.007%)
Channel separation: >85 dB
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