Hi! This is my first post on the forum but I've visited head-fi many times as a reader. I've used a pair of HM5 (the lindy premium version) for some years and now I was looking for an upgrade. I read many good things the DT990 pro (250ohm version) which are about 130$ at my local amazon. The thing as you know is that people disagree wether or not this headphones can be powered by a cheap dac/amp such as the fiio e10 (some say it does sound really good on it). Another option would be the Shiit Fulla 2, which I can get for around 160$ (i'm in europe), which spec-wise should be able to power them. I could make an effort and go tor the fulla 2, but only if it would really superior to the e10. Still some people say that you won't really get the full potential of the beyers (which btw i don't think my ears will be able to appreciate) if you don't have a tube amp. So my questions are: 1) are the dt990/250 worth it if I don't want to spend more than 150$ on dac+amp? Is this whole concern something for demanding audiophiles? 2) If I decide to go for the e10, will it still be an upgrade from the hm5? 3) Same question but with the fulla 2? I also had a strange idea and I don't know if it makes any sense (i'm a total noob as you can guess): I have an old '80 pioneer a-40 speaker amp like this one https://www.hifiengine.com/manual_library/pioneer/a-40.shtml What would happen if I pair it with a e10? Thank you!