If you tape on Google DIFFERENCE BETWEEN XLR AND RCA you will have tons information ALL THE SAME from different sources the XLR are much much better with sound and quality then RCA
Here's the deal - You're reading too much into things.
gave you a very reasoned response earlier in this thread, and hopefully I can as well...
If you're unsure of what a technology actually provides, then reading is good, but asking questions is better. Is XLR better than analog RCA? Yep! Sure is! XLR connections can go hundreds of feet and have built in analog noise removal as part of the technology.
So... All concert artists must use XLR right? Nope! They use digital. The entire world has pretty much moved to a digital audio chain because it is basically noise free. A digital connection over a RCA cable is not actually susceptible to noise. It can have digital audio dropouts, but it really doesn't get noise into the digital audio at all. Optical can go hundreds of feet without any digital loss....
But, are you going hundreds of feet? Dozens of feet? Or less than a few feet?
THIS! This question is what matters: HOW LONG IS YOUR CABLE GOING TO BE?
When you finally realize that you aren't dealing with long cable lengths, you realize that the potential gain/loss in the audio quality is going to be incredibly small. To a point of being inaudible. But... WHO CARES?
The golden rule is to use the best possible connection for your specific equipment type. If you want to use the DACs in your CD player, which is perfectly fine, then use them, and then the ONLY way I would make an analog connection is to use the XLRs. They ARE there, and they ARE the best connection. Even if they don't audibly sound one bit better, there is no reason not to use them over the RCA analog connections.
If you would prefer to use the DACs in your AVR, then I would use either the optical or the coaxial digital connection. Both of them will provide an identical audio experience. IDENTICAL. Don't get fooled into thinking otherwise.
My opinion? You've paid for a high end CD player which has excellent DACs in it. So, I would use them, and I would use XLR connections between the CD player and the AVR because they are available. This gear isn't cheap, and it works well, so make use of it. But, don't actually think you are getting a 'far superior' experience then if you had just used optical or coaxial digital, or even the regular analog RCA connections. It just isn't reality.
Above all else - absolutely do NOT overpay for your cables. Decent cables, at a fair price, are available from a long list of manufacturers and they all sound exactly the same. It is standard practice to use very thin cabling for XLR, because it specifically doesn't need the shielding that RCA cables need. So, buying a really nice XLR cable may make you feel good, but will do nothing to improve audio quality.
The end game for you should be the best possible audio quality, and this will happen when you use the best connection. But, the ACTUAL audio quality you get is likely to be nearly identical and should really have zero real world audible difference when using the different connection types. Instead of arguing about what you're reading online, I would just get a XLR cable and some RCA cables as well as an optical cable and just try them all out. Call it some money spent on a learning experience. You should NOT pay more than $10 per cable. If you read that expensive cables are better, that's a serious error. Then, do some testing yourself. Don't be fooled into thinking that more volume is the same as higher quality. That's not the case. But, certainly, I would likely hook up those XLRs and call it a day, even if they don't sound any better, they are a great way to get audio between the CD transport and the AV receiver.