Listen to them on a hi-fidelity stereo system with hi quality speakers in a balanced sound set up, & then compare them to the original CD, & you'll notice a lot of difference in quality. Most notably loss of both high & low frequency range, loss of sound separation, loss of overall sound quality. A direct comparison using good listening equipment is the best way. Even sub-standard listening equipment will show how much considerable loss of quality there is.

But if you're happy with it, then that's fine. I'd just suggest you don't re-share your re-converted files. That "would" be unfair to those who are looking for reasonable quality files to get a hold of. Share your originals instead. (hint)