Hi,
I've had the DT1990 several times for business. The JDS Atom stack works really well, and the soundstage was little better than the Topping L30/E30 which is nice, but couldn't find any filters beside 2 or maybe 5 that were ok. The Magni Heresy and Khadas tone board were a great combo with them. I currently have the SMSL SP200 and still have the tone board on it, but if I got the DT1990 again I'd match it to the Magni Heresy. Any of those amps will drive them. They do have a hint of sibilance in bright tracks, and the Heresy is more forgiving than the Topping. I have a Magni 3+ Modi 3+ coming in a few days, and going to pair them with the 250ohm DT990's and the DT880 I have here. It's stuck at the Richmond VA USPS hub for a week, so should be soon and could tell you how they work with those. Haven't tried thee DX3 Pro yet, but I do have a D30 I was trying this morning with the JDS Atom amp.