I've only met with frustration in trying to record on my iMac, using 9.2.  I have a Yamaha P-80 with midi capabilities. To start, however, I only want to record audio and make a  basic demo CD. Hope someone can help.
......I have Cakewalk's Metro 5 and downloaded SoundRecorder 1.0 (freeware, very basic), thinking that the only reason I've been unable to record is my lack of experience....I am new to Mac. Here is what I'm doing.

One end of a cable with a 1/8-inch plug is in the computer's Mike port. The end connected to the computer has two stereo plugs, one left and right, for the keyboard's output ports. It appears sound is registered on the software when I play. However, there's no playback. I'm using the internal soundcard. I only get loud static, with an annoyingly loud noise from the left speaker....The Apple Store checked my computer the sound card and port are okay....What do you suggest  ? Please don't hesitate to share even the most basic info. I'm on a steep learning curve...Thank  you, gracias, merci, grazie, obrigado !

Hi jodc, Recording audio using metro 5 can be tricky at times, but it's what I use, and once I figured it out I would not have it any other way. So I'm going to give you the complete rundown. You may have already done some of these steps, but I'll go through all of them.
First off you do have you yami correctly hooked up to the computer.
Go to your control panel and go to your sound, make sure that sound in is checked and that playthrough is checked also. Play the keyboard and make shure that you can hear it coming out of the computer (headphones come in handy at this point).
Now then start up the metro 5. Usually at this time it wants to know what midi port you're going to be using, just click OK and move on. Now that the program is up, look at at the tracks and see what port it says it is using. If it does not say audio port 1 do this: click on whatever it says and hold the mouse down, a box will appear with a bunch of ports. Place the mouse over 'edit port' and release. Now then a box will appear, click on audio and OK. Now go to SET UP in the menue bar and select digital audio. In the box you will see a recording options button, click on that. Make shure the playthrough is checked. Now is a good time to check your recording level. Keep it as low as possible, or you will get alot of hiss. OK every thing and you should be where you need to be.
Make a recording, wait for it to build an audio overview. Now hit play. You probably still won't hear anything, but don't have a cow! Go to file and export the audio file you just made. Once you have done this go to edit and delete the track you just made. Now go to file and select import audio file and import the file you just exported. Wait for it to build an audio overview. Hit play, at this time you should be able to hear your recording. If not, you did not follow the instructions....start over. Once you are able to hear your recording, you should be able to record your next tracks, and be able to hear them without the exporting audio file thing. I do suggest exporting all tracks as this saves you from goofing them up. If you do mess up a track and you already have it saved, all you have to do is delete the messed up track, and reimport it, good as new.
Now then, there is a ton of other tricks to go over, but I'll save them for another time....have fun!!!!

Thanks kaboombahchuck. I feel like I've found a lifeline and may have finally spotted the technical problem.....I checked 'sound in' and 'play through.' (That alone was a big help since before I had checked 'external mike' !) Unfortunately, no sound came through the computer speakers after that. But I'm suspecting the plug into the mike port may be the culprit. First of all, when it's plugged in that's when the horrible feedback in the left speaker begins and the sound register jumps all over the place, even without playing a note....
I read--- can't recall where---that 1/8th inch plugs have two lengths, one a bit longer than the other, and that sometime the length (of the metal part) affects a sound connection. Maybe the computer needs the longer version ? My 'short version' is about one-half inch. I believe the longer version is around three-quarters of an inch.
I obviously need to get past this point in order to follow your other wonderful recording tips.

Any ideas about my connection issue ? By the by, I have tried another
1/8th-inch plug (short version) and still had no results..
On the road to recording.....thanks again.....jodc

As far as the 1/8 inch jack goes, it needs to be exactly like the ones used on head phones, in every detail. If your 1/8 inch jack matches, let me know, and I'll take you through a trouble shooting rundown to find out exactly what is wrong. Make shure of the match, two color bands (usually black), or three metal conectors, and the right length.

Thank you, thank you Kaboombachuck. I do believe my plug is the wrong kind. It only has one stripe. In the next day or so I plan to hoof it to Radio Shack and get the right one. Will let you know results, when I'm ready for Part II of recording on my iMac !!