Audio Delay - Clean OSX Install

Hi All

I have directed this question to Google / Logic users but get caught up in a strictly 'delay effects' trap. You'll see what I mean when you read the problem.

I have Logic Pro installed on Mojave 10.14.6 and whenever I use headphones and just the metronome there is a strange audio delay. Its very short but is also present when using loops or any other osx application with audio output. I used an alternative audio interface and this resolves the issue but I would like to use the macs headphone output especially whilst traveling.

Here's the interesting one for me - I have reinstalled Mojave on a separate, clean drive and then followed by Logic as my test to see if it returns and hey ho its not there. You may say just do a clean install on my mac but I'm very curious to find out what this could be. I'm not a coder but a long time mac/audio/educator and would be good to share with students.

Any help much appreciated.

Jasonix