I haven’t used Clipchamp for this, and the last time I really tried using VLC for that purpose, I wasn’t successful. I have had decent results with FFmpeg but had to change the audio encoding in order to get that work, and that shouldn’t affect the video stream of the finished product. One of the Forum Mavens created a Web-based tool that you could try to see if that produces any better output. Like @dave27, I wonder if some switch you’re using is reducing the quality of the output, particularly with an online tool. When you have access to all the files locally, I prefer to use a tool running on the local machine for maximum control, so FFmpeg would probably be my first choice.
Welcome to the Forum, @Larr! 