We have a USB splitter that connects an external hard drive to two separate computers (MacBook Pro and an HP Laptop). Unfortunately, the USB splitter is emitting an electrical buzz that is picked up in audio recordings on the MacBook Pro only. When the external hard drive is connected directly to the MacBook, there is no buzzing noise picked up on the MacBook and the audio quality is perfect. However, when the usb splitter is added back in, we get the electrical buzz again. Any thoughts on why this is happening or why this is happening only on the MacBook Pro?