How can I go about using an eq on my Dali MS 4.

Adding another component in the signal path to reduce something does seem counter-intuitive to me as well, because ultimately it’s adding some level of unwanted noise which is likely most obvious in the treble range, but I suppose it depends on how much of a purist you are.  EQs are really just versatile tone controls, but a lot of the cleanest sounding gear doesn’t have them. 

Decades ago I ran an EQ through a tape loop and cassette player on my receiver.

I'm using an equalizer with my vintage amplifier. To me it sounds more pleasing.

I'm thinking about adding an equalizer to my modern amp as well.  I'm going to run an RCA cable from my wiim to EQ line in - and then line out from EQ to aux in of my amp. Will see if that works..

If you’ve aimed the speakers straight ahead with no toe in and they’re still too bright and also need help in the mids I’d cut bait and get new speakers and stop fighting it because that’s a lot of critical stuff going wrong.  Failing that you could try one of the equalizers from Schiit and return it (minus restocking fee) if it doesn’t do what you want.  

 What are you using for speaker cables ?  Owned those speakers in the past and found them very responsive to cable choice. 

Some modern amps don’t easily allow the insertion of EQ into the signal path.  So please share with us what amp you use, and also what your comfort level is with computer technology, because DSP based room/eq is a thing that might help…or terrify…you.  The Schiit Lokius is what I use, and it is super simple if your gear has the right connectivity.  McIntosh has some models with similar facilities built in.