RCA to XLR Adapter

If you make your own, be patient, twice check your connections, and try one channel at a time. 
If you get hum, obviously something is incorrect, check again😊
Been there, ”doing that,” satisfied w/the results. One day I’ll upgrade the cabling. Right now too many other, bigger fish to fry. 
Tony

https://www.neutrik.com/en/product/na2f-d2b-tx
https://www.neutrik.com/en/product/na2m-d0b-tx
I use them without any issues.
you have XLR male or female input choice.

You will always loose sound quality with adapters no matter how good.I think you best bet is to look at an amp that does single ended well such as PASS etc. 

ebm6 is correct - adapters in the path will degrade SQ

Concerning the “mixing and matching” connecting single ended to balanced or the reverse - some degradation can occur. 
My cables are the adapter - XLR on one end, RCA one the other. My balanced gear is forgiving - some is not😡 As I posted, one day better cables w/better connectors. Better ingredients better 🍕😊. 

@ebm  +1
I use the Neutrik between my HT Processor and the subwoofers.
Loosing sound quality there is not that important.