I think for your application, you'll just need to separate the concerns out a bit You have the mic preamp, which can definitely be diy'able Then you have the

I think for your application, you'll just need to separate the concerns out a bit You have the mic preamp, which can definitely be diy'able Then you have the AD/DA converter - this will convert the output from your diy'ed mic preamp into digital signals - this can't be done easily DIY, but you can purchase chips that does this : the ESS Sabre is one of the most popular AD/DA converters that you can probably source from aliexpress, etc - you might need to buy in bulk though otherwise the vendor might not talk to you. Then you have the usb interface itself, which comes with all the issues about certification, interface types and properly engineering/building a usb interface that works with consumer ports across different platforms is non-trivial for DIY'ers. You might be able to do something like "make a usb work for my specific computer, with a specific motherboard/platform" but for example, making something that adheres to the usb2.0 or 3.0 spec for both mac + pc + anything else that uses usb (for example, your cell phone, etc) - that's a totally different exercise that most diy'ers won't be able to easily do. Again, you can buy off-the-shelf chips to do this, but at that level, you're doing digital circuitboard design, and I'm not sure how well bread boarding works with things like usb. You might be able to layout a PCB and have someone etch it for you, etc. After that you'll need to build the output portions of the interface (after coming out of the DA chip). That can be DIY'ed. If you want to DIY an in-and-out audio interface you'll need to take on all these different aspects all at the same time. That's why you don't see many DIY projects of this kind. Rather, the DIY projects being talked about in this thread are one aspect of this chain: you want to drive some speakers, ok! we can build an amp diy. You want to do AD/DA ok you can do that one thing with a homebuilt board, with a chip, etc. But having all aspects being integrated together is non-trivial for a DIY. You might be able to use a Raspberry Pi zero or something like that for driving the AD/DA - USB portions, etc and that could be a way to go. In fact, I think using an RPi as a DAC would be a great way to DIY a usb audio interface, at least you've got all the chips integrated already, and you have an audio jack for getting inputs, etc, and you have the power source and usb OTG port[1] already designed, etc. And that's where you start to see $100 isn't all that bad for a usb audio interface. [1] https://gist.github.com/gbaman/50b6cca61dd1c3f88f41 https://gist.github.com/gbaman/50b6cca61dd1c3f88f41