If your doing sound the imac is fine. Reason has very low recommended specs. Logic runs fine on my macbook so i wouldn't see it breaking sweat on an imac. Only thing i would worry about is running out of ports seeing as an imac has 1 audio in and only ends up with three usb after the keyboard and mouse. You can get some cheap usb hubs or even a external sound mixer thingo (i forgot the proper name).