Hi Mike. It sounds like your internal sound card is operating at 44.1Khz not the 48khz that your project is set to. A similar thing can happen if you mix at 44.1 and export at 48 but it all sounds sped up. See if you can change the sample rate for your internal sound card to 48k. This is an educated guess based upon something I saw on youtube recently. (I think it was a Joe Gilder Video either on his own channel or Presonus own channel). Another educated guess would be that the timing is slightly off and it sounds ever so slightly flat, making it all sound out of tune? But I would imagine that, like me, using an interface as a daily driver you don't even consider the operating system settings for sound. I can only advise you about windows based systems and I don't really use Apple Hardware or Software. I know most modern windows motherboard sound chips can support upto 48k at 24 bit. Essentially bluray quality HD sound. Can't speak to what Apple hardware does. Hope that helps. Jake.