Different strokes for different folks. Well, usually people find out that maybe more equipment is needed in the long haul. That is because recording is different than playing live. I have an amp that has low impedence outputs and can set the volume like yours. It is a modeling amp Fender. I also have another amp that can record out of the headphone jack and sound like the amp with the cabinet. That is also low impedence or around 30-50 ohms, and also the headphone jacks on the Babyface work around 30 ohms also.
But then, after you record you may want to compress the signal going into the recording, so either you can do that perhaps in Logic or the other but then I use Sonar so I am not sure what you get with the recording software. I also have a Windows computer so all that would have to be checked out for the Mac, but the Babyface and RME come out with drivers to suit the purpose.
The only other things I use are a Digitech box or a Boss ME-25 like or some other effects which usually by the way can be stereo in the output and all that has to be considered.
I have channel strips also which are low impedence outputs and the Babyface Analog 1 & 2 inputs support about anything, and the guitar unbalanced input on the side of the Babyface with the high impedence is more perhaps like a guitar naked then you may have other tools in the software to similate amps or distortion and other software with the say Logic program to make the sound different if you want that.
So that usually leaves the low impedence XLR inputs (analog 1 & 2) on the Babyface as the main inputs and the channel strips have compression and EQ in there and all of that so the recording comes usually out better if that type of equipment is needed.
Depends on how you will record in the end - loud and compress and the loudness wars that seem to generate nowadays with recordings or perhaps more like old analog type recordings in a sense but then it is digital and not analog like tape in the Past although Sonar has tape hiss kind of sims and cabinet sims and EQ and all that kind of stuff included with the program.
Well, how you record at least to me will be different than live playing, but the headphones out in the guitar amp the speaker is cut-off, and I am not sure about the low impedence outputs on the Fender Mustang III V2. but I suppose the speaker is also cut off when hooked up that way perhaps not, I found out the speaker is not cut off by those low impedence outputs made to go into a mixer board say for loud playing, but both have a headphone jack that can be used for recording also (mini 3.5mm plug).
Of course if you were in a recording studio you may have an old beat-up guitar and a mound of equipment like in this video packed in sort of like sardines in a can.