Yes you can record raw vocals through the A/D inputs using MODX straight to a DAW. Most easily by routing the A/D Inputs to output to a pair of USB channels.

The MODX A/D inputs function as an audio adapter when you route the A/D input's output to USB. If MODX's audio adapter is better than some other audio adapter depends on what audio adapter you're comparing to. And some of the determination of "better" is subjective. Also, your vocal microphone may or may not be a "best fit" for the unbalanced, unpowered inputs provided by MODX.

MODX's A/D input is not balanced. Some audio adapters provide a balanced input. Many vocal microphones have an XLR/balanced output connector and other audio interfaces have options for XLR inputs. So these audio interfaces may be a better fit for those microphones. Also, some microphones require phantom power and other audio interfaces may provide phantom power - also a better fit. That said, your vocal microphone may be unbalanced and require no phantom power and just plug right into MODX. If this is the case, then MODX would be no better or worse on this front.

In the subjective department - each audio interface sports different preamp or A/D circuits. This is proprietary stuff - and some may "sound better" to some or worse to others. Different audio manufacturers may even have a fancy marketing name for their circuitry - and sometimes favorites of these reach legendary status. In the end, it's your opinion.

You didn't want any effects - so comparisons on quality/availability of effects in audio interfaces vs. MODX will be ignored here.

And finally, there's the raw numbers. Sampling rates and bit depths. Those you can compare specs although - like cameras - more megapixels isn't always better. And in audio, faster sampling rates or more bit depth is not necessarily better. It's in the implementation. Noisy inputs or non-transparent inputs can ruin the paper specs.

MODX is no slouch as an audio interface. You can spend just about as much as you want on a dedicated audio interface. Some may be "better" depending on what you're after.

Thank you for your response, Jason! Much Appreciated.