Recordings? I doubt it as until about the 10th century plainchant was passed on orally. The earliest manuscripts date from around the 10th century. This would be the antiphonale of Laon, and is one of the sources of Solesmes restoration of Gregorian chant late in the 19th century. However, we can’t be certain that the Solesmes method (or any other for that matter) sounds exactly as the free-form neumes of the 10th century were interpreted.
Some old hymns go back still further to the Ambrosian period, especially for the Divine Office. I can think of two hymns for Holy Week, Vexilla Regis and Pange Lingua (about the Cross, not the Eucharist, the latter Pange Lingua was an adaptation by St. Thomas Aquinas). Those go back to 6th century, and were composed by Venantius Fortunatus.
If you look at the current Graduale Romanum, in the Kyriale the approximate time of composition of each Mass setting for the ordinary is given. Most are 10th to 12th century.
Keep in mind too that there were various rites back then; until Trent there were the Old Roman, Gallican, Ambrosian, Mozarabic, Old Sarum rites, just off the top of my head. Each had their own distinctive chant forms.
The evolution of the Mass is a pretty complex topic, I am sure plenty of doctoral dissertations were written about this topic!
Here’s an interesting timeline, placed in the context of other historical events:
Timeline