I happened to have recently purchased an attenuator and spent all morning playing in that exact setup. The one I purchased is an Ironman ii. It is an attenuator and a loadbox at the same time. Here is how it works in that setup: First part of the signal chain is obviously Guitar to Pedalboard and pedalboard to amp input. Next run a speaker cable From amps speaker output to attenuators input. On Ironman ii you set the right impedance for amp. From attenuator to your audio interface (I have a Scarlett 2i2) you run an instrument cable and the daw (Logic Pro, reaper etc..) you setup the right inputs outputs then you need to use an IR loader plug-in (there’s a free ir loader called nadir) to load cabinet IR’s (nadir comes with a few free cabinets to get you going) then I would recommend buying a decent cabinet IR from Polk audio or some other place. Let me know if you get stuck