Hi there
quick question for Video gurus out there

I've a load of X-264 mkv 1080p files (approx. 2GB) each . In preparation for new 4K transmissions etc I want to convert everything to the new HEVC X-265 standard (VLC plays it fine) which makes the files a LOT smaller - typically 5X !!!. Can I convert existing files without losing quality and what's a good tool to do it with.

I've been using MAKEMKV for ripping DVD's and Blu Rays but it doesn't rip to HEVC X265 and nor does Handbrake..