Hi looking for some advice on expanding my recording setup to four channels. I have an Audient ID14 MKii that I am very happy with for recording my classical guitar and vocals. I recently got a pair of OC818's and to make use of the dual outputs i require four inputs. Any recommendation on whether it would be better for me to buy the new ID48 once available or rather get an external preamp like the SSL PureDrive Quad and connect that to the ID14 via Adat? Thanks in advance.

Different flavours of stuff via ADAT/MADI (depending on what you have in the future as well) can lead to a nice, flexible, modular setup.

I use an RME Digiface USB - 8 ADAT holes, and can connect whatever has ADAT.

Mix and match as needed.

you don't want "pure drive" preamps. those have a switch that adds distortion to the signal. you don't want that on your classical guitar, and you don't want that on your vocals either. you would be paying for preamps that are unremarkable, and for distortion circuits that you won't use.

this is what you want. four channels of world-class clean preamps. used on top-level classical recordings for decades, and found in fine studios throughout the world. you don't need ADAT or any other digital contraption. you run the output of these preamps into the line inputs on your interface:

https://www.sweetwater.com/store/det...v-3d-4-channel

what you have right now is fine. if you don't have money for the above product right now, wait and save. this is the droid you are looking for.