After listening to hours of audio books and building my studio, I find it is possible to worry too much about audio quality. The noise floor in your studio only has to be good enough. Because the broadcast medium or network connection that sends your work to consumers will almost certainly be noisier than your studio. Additionally, your microphone, interface, and recording software need to be good enough, but you don’t need a $10,000 recording studio to make good voice over recordings: this is the 21st Century, where people record wildly popular video and audio using only their smartphone. This doesn’t mean you can be a successful voice actor using just your smart phone. You need to be sure your technical details are good enough: your hardware, your recording space, your production processes, etc. But they don’t need to be better than that.
What matters most is your skill as a voice actor. In other words, can you deliver a performance? This is the skill that will set you apart from other voice actors and voice over artists: because everyone who is staying afloat in this business has acceptable recording quality and hardware. But really successful voice actors can sound good if they’re recorded through a 1960’s tape recorder or a state of the art digital recording studio.
Think of it this way. Let’s say Jimi Hendrix was still alive. You give him a $100 guitar and asked him to play, he would make beautiful music with that cheap instrument, just like he would if he had a $5000 custom Fender Stratocaster, because the artist’s skill typically matters more than the instrument. Can you make your voice sound good whether you use a $100 mic, or a $5000 one?