As noted, it is up to you to decide whether or not you can hear (or see) a difference between Cat 5 and 6. Unlike the dynamic range for perceived volume where you need headroom above the average playback volume for peaks, the streaming signal doesn't exhibit that trait. If you are watching a 4K video streaming at 25 Mbps, you don't need another 50% or 100% for headroom. 25 Mbps is the max.
If you want to play 192K/24 music, the max stream rate will be under 5 Mbps. With a 100 Mbps connection, you'll be 20 times that. Not sure why one would need more if that is all you're doing. My two cents is, if there is a sonic issue, it has more to do with EMF/RFI than speed.
The really high speed connections are great when you are transferring big files and want them to download or upload as quickly as possible, but that's not a real-time playback issue. And, as noted before, higher speeds can be nice when you have a lot of people in the household online at the same time, each doing their own thing. Who else is going to be using your particular run of Cat cable?
