Assuming you also have active monitors connected, I wouldn't use the XLR outputs, then you would have the operational disadvantage, having to disconnect and reconnect one of your active monitors again and again.
Using the headphone outputs would be possible, but you might still need the phones outputs.
Even if you would use the 2nd phones output they are coupled so that it is unlikely to get a good setting which fits phones and the line input of your guitar.
You might have to buy a separate volume control for the phones to be able to keep the output for the amp high but the volume for your ears low. Something like this phones extension cable with volume control: https://www.amazon.de/Valueline-VLAP220 … amp;sr=8-3
Maybe a better idea now and long term would be to sell the BBF Pro FS and to get an UCX II instead.
Then you have all the inputs and outputs as needed and even more in a small case.
Plus excellent Mic inputs, Autoset and DURec.
Then you can keep everything connected, have a separate mono line out for your guitar amp and for every channel you have in TM FX a dedicated volume control.
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13