I checked out eqMac (thanks David) but there were too many negative reviews for me to consider downloading it. The Audioscience site (thanks Daverz) had a lot of options for Mac and it took me a while to check the main ones out. I eventually settled on SoundSource
https://rogueamoeba.com/soundsource/It's a paid for app but the sound I heard in the trial version using Deezer was very impressive so I've pulled the plug and spent the dollars. It has far more features than I would ever use but it does two things that I really like.
First, it totally bypasses Mac sound card and a lot of other things as well. (Think using WASAPI or ASIO for PC) My attached Burson Playmate2 does most of this but while it's close it's not bit perfect. SoundSource solves this issue which is why I was impressed on first hearing.
I have the ability to have separate settings for all of my music output. I can have one for Deezer and something different for my VLC player.
I wonder if I can eq for my different headphones using this app?