IR/Coaxial and Optical input/outputs?
The reciver I have is like 20+ years old so some of this stuff is new to me when I upgrade to new units which will be the NAD C352 Integrated Amp and C542 CD player.
On the Amp it has IR input/output and the player has Digital optical and coaxial digital output.
Im guessing the IR hooks to the optical on the cd, what about the coaxial?
Is the Optical a better connection that cables? or is there any diffrence?
No. IR has nothing to do with digital sound at all.
That IR input/output is, I believe, a means to use one remote control to control several devices. I know Pioneer had some sort of thing and NAD has what they called "NAD Link" whereby one remote could control several devices.
i.e, my NAD 616 cassette deck did not come with a remote control or an IR sensor but the remote included with the 1600 tuner/preamp can control it to some degree via a similar system of daisy chained wires terminated with yellow RCA plugs.
Your manuals should verify this.
In any case, there is no connection between digital sound and Infra Red remote control jacks.