Taylor 114ce -- how loud to record?
 

I just got a Focusrite Scarlett 2i4 for my iMac.

Taylor 114ce => Mackie 1202 => Scarlett 2i4 => iMac => GarageBand

I made a 4-track recording just for fun.

Should one play the guitar as loud as possible? or play normally and adjust the volume level with the mixer or recording software?
I record at night is hard to make lots of noise if people are sleep...

Even though I have used mac computers since 2003 I have never used GB

That said, in general as far as digital recording:
No you should not (play the guitar as loud as possible ) Yes you you should adjust volume in the recording software . With digital recording the signal should not be approaching 0 db on the meters
(unlike analog tape there is no headroom above 0 db in which to soft clip) In digital once you hit 0 your signal will clip (distort)

Now unfortunately there does not appear to be a scale on the meters in Garage Band, which is decidedly less than optimum for recording, especially for multi track recordings.
But it looks as if the rhythm track signal is getting dangerously close to 0 so it is probably too hot.
Also it look's as if there is no master output track so the only indicators of total signal level, appear to be the meters in the transport, which look as if they are clipped (hard to tell in the video but the little dots at the right side of the meters look like they might be lit red ?)

The Scarlett 2i4 has instrument inputs and preamps, so what's your reasoning for using the Mackie 1202 in the recording chain? If you are having issues/questions regarding recording levels it may be helpful to reduce the number of devices in your chain the minimum required.

Chuck is correct - there is no real reason to use the Mackie in that input chain. Are you using to EQ the signal?
BTW, you'll get a better acoustic sound by miking the guitar rather than recording the DI signal.
When recording digitally, your signal should be in the -20 to -12dBfs range. You should never be getting close to 0dB during tracking or mixing, that extra volume increase should only be done at final mastering.

You should play the guitar at a volume that achieves the best tone, and your levels should peak at roughly 2/3 - 3/4 the way up the meter. Of course, you should experiment with mic positioning and distance until you've found the "sweet spot".

I agree that the onboard preamps of your interface are probably every bit as good as the Mackie preamps, so you might consider eliminating the Mackie from your chain. There's a whole world of nice preamps that would be an improvement over your interface's pre's, but the Mackie might just be a lateral move. That said, If you want to use an external compressor or EQ up front, you would need to use an external preamp, and your Mackie would work just fine for that.