An NDA isn't needed here. I could see one being required if you were laying down tracks on a big budget production, but if this is just you laying down drum tracks for some guy, an NDA seems like overkill.
People are often confused about certain aspects of intellectual property laws (eg. copyright, trademark, patent, etc.), such as when they arise, how long they last, and how they can be extinguished, for example, and about how remarkably different they are from one another in terms of them. Your potential client's copyright arose the moment he created the work at hand, and all the rights that flow from it arose the moment the work was created. Filing is not needed to establish copyright of his work. Although filing was once done to provide evidence of the date a work was created, it's not as important in today's digital age, provided one has a digital copy of the work establishing the date it was made. Your potential client sending you a piece of work that neither you nor anyone else can show was created before he sent it to you is good evidence of him having created the work. Consequently, he would already be in possession of any rights flowing from the copyrighted work, and no written agreement would be necessary to establish that.
But filing a copyright can grant global protection, as long as the country you file it in is a member of WIPO. Realistically, though, if you're at the stage where you're filing copyrights for musical works, chances are you've already made it and have representation to take care of things like that for you. I don't know any amateur, or even semi-pro, musician - or artist, for that matter - that files copyrights of their works.
That your potential client is asking you to sign an NDA suggests he isn't well versed when it comes to things like this, or the scope of his work doesn't merit one. Either way, it's reason for you to not enter into an NDA. But if you do enter into something in writing, do not draft it yourself and present it to him - at least, don't draft something that he's asking for his own benefit. It's a general rule in law that any deficiencies found in a contract are held against the person who drafted it.
If I were you, I'd let this guy know that you'll agree to delete all copies of his work from your devices immediately after you've finished laying down your tracks and have been paid for your services. Do the job, get paid, keep your word, and there should be no problem. If he insists that you sign an NDA before he hires you, make sure to read it thoroughly and refuse to sign anything that doesn't sit well with you.
