"Using tunes of people that are not "people of Torah", even if the words are not assur, could possibly be considered to be like "enjoying from the meal of Achashverosh".Rav Steinman's analogizing the use of secular melodies to "enjoying from the meal of Achashverosh" is interesting, especially since the Megillah omits music from the description of luxuries provided at Achashverosh's feast.
"The fact of their participation [in the party of Achashverosh] alone was problematic, even if they had not eaten anything that was non-Kosher. The same is true with enjoying things that are not within the spirit of Torah even if they do not have anything specifically assur about them. The same is with using tunes of people who are not living lives dedicated to Torah... even if there is no actual Issur involved. It is worse than any specific issur, because everybody knows to stay away from an issur. The moment non-Jews act in a certain way, we must stay far away from it so as not to be as if "enjoying from the meal of that Rasha [Achashverosh]."
In "The Power of Music", I quoted Rav Matisyahu Solomon, who asks:
Why didn’t Achashveirosh provide any temptations for the sense of hearing at the party described in the beginning of Megilas Esther? He provided temptations for all of the other senses; smell – scents from the garden; sight – beautiful tapestries to see; touch; luxurious gold and silver beds; and taste – “Yayn malchus rav.” Why didn’t he provide music to tempt the sense of hearing?Further, he asks:
R' Salomon asks: The Nesivos (in Megilas Sesarim) explains that Achashveirosh’s intent was that each thing would incur a direct violation, for example, he had prostitutes there to tempt the people, so why didn’t he have musician’s playing erotic music? We all know the power of music in being moshech people to ta’avah.So, according to Rav Solomon, one can derive the exact opposite from story of Achashveirosh's party; that even secular music can be used in a spiritually positive way.
To answer, he [Rav Solomon] quotes “Zaken Echad” (based on Radak) who says that we’ll never totally understand Tehillim until we understand the musical instructions and instruments assigned to each piece. The power of a nigun is to add “hesber v’havana b’dakus hadevarim.” To this point, the Meiri explains the pasuk of “Zamru maskil”; that singing gives insight. However, it only gives insight, or is meorer that which is hidden in our hearts and souls. In other words, R' Salomon feels, a nigun is neither tameh or kadosh, rather the tune is meorer what’s in one's heart. Even if a given tune is meorer some to ta’avah, nevertheless, the same tune can bring an Ish Kodesh to dveykus.