I was cautioned against DIY recordings for prescreen. We paid some of our son’s teachers from his prep program and used a local music schools recording studio. It took one evening and it was slightly on the pricey side but nothing compared to tuition (LOL). More importantly our son passed all his prescreens. Working in a real recording studio is also a good experience for your child. If money is especially tight then consider hiring local younger musicians to accompany your student and using a recording studio at a local college or school.