Yes, you can use the AUX input for a cd player. The 2325 is quite the powerhouse, enjoy it!
Not meaning to argue w you, ZD and admittedly w/o any personal knowledge of that unit, I'd not be so sure that it's inferior to modest priced current MM stages. Remember that there were no CDs back then, so phono stage performance was very important. If the parts have all been checked and upgraded/replaced as needed/possible, I wouldn't count it out w/o having listened to it. For all the reasons that many others have articulated here, I'd go w a high end MM or MI cart, rather than an HOMC.