There is an important aspect of the problem some have with non Jewish music that many people don’t seem to realise. Ultra orthodox Judaism is based largely on the idea that in order to prevent Jews becoming irreligious, it is necessary to preserve the culture as much as possible. This includes a dress code, various traditional ideas such as anti Zionism and the great stress on the importance of spending time in Yeshivah regardless of actual success, depending on the community and the level of barriers erected to prevent Jews from leaving the community.
The same idea applies to music. This is why many will find no problem with Jewish singers, but non Jewish singers with the same song or even classical music will be considered as wrong and somehow inappropriate. Some will even justify this with kabbalistic concepts of of somehow purifying the “soul” of the song through the holiness of the Jewish singers who may need to be a great rabbi, depending on your beliefs. You may believe that, and there is no way to disprove it, since holiness is such an elusive concept.
