You want to listen to a podcast about songs? Instead of just listening to the songs? Am I missing something?

The HD560S is already a very good headphone. It’s totally reasonable to just prefer the sound of the HD560S over the Sundara. I wouldn’t go down the rabbit hole of trying to get new amps until one makes you like the sundara.

IEMs are literally just about getting a tuning that works for you.

I bought both blind at the same time and frankly I think the amiron is one of the worst sounding headphones I’ve owned. I sold it within a few weeks. The midrange is far too recessed and the weird hump in the lower mids sounds extremely wooly and muddy to me. The DT1990 is much better in this regard but still has a fair bit of it going on.

To be honest the DT 900 pro x blows them both out of the water for less money and I think the DT 900 pretty much obsoletes both the 1990 and amiron.