I’m using an iMac (10.6.8) and a non-USB turntable hooked up to my amp/receiver. When first trying to use Audacity I got no output sound but I was lead to ‘LineIn’ and that solved that problem. Even so, I did see both channels getting the signal even though I couldn’t hear anything. Now, however, I can’t get both channels to record. I get what looks like this: (Hope you can open it). And yes, all my settings are correct. Any suggestions?
Thanks in advance
That’s not visible to me.
On the Audacity main screen look at the pulldowns to select the recording source (microphone symbol) and right next to that, you can select mono/stereo.
If all that’s correct, make sure the plug behind your iMac is all the way in.
Audacity > Preferences > Recording > [X] Playthrough (select)
That will let you hear what you’re doing.
Well, the sound playthrough problem has been corrected. As you can see in the image it appears that only one channel or the other is recording. The horizontal bars in red at the top are very uneven in their length which, of course, corresponds to the volume in each channel. I realize that I can INCREASE the overall loudness by dragging the microphone to the right but how do I increase the volume/loudness of either the right or left channels separately? In almost every youtube video I watch the red bars of the input are always equal in length, i.e., volume. Am I making any sense? : 
Thanks
Check the plugs and leads - the left channel is so low it may be due to a faulty lead or a faulty connector.