My great aunt, Dorle Soria, was the founder of Angel records. As well as being a producer, she also was looking for talent both new and established and was instrumental ( no pun intended ) in helping new talent get recorded. I can't attest the sound quality of all the recordings, but the ones I have sound pretty decent on my system. Although I may be biased.It seems that the Soria's did a fine job of distributing classical recordings in the US for EMI.
At some point EMI/Angel stopped importing and began production and distribution in the US only. This is when different masters were used to press vinyl, and to my ears, never matched the quality of the original UK masters.
https://en.m.wikipedia.org/wiki/Angel_Records