I built the nwavguy O2 kit from jdslabs and like it. It does perk up the Sennheisers and would probably work well for your headphones. I don't hear a lot of d

I built the nwavguy O2 kit from jdslabs and like it. It does perk up the Sennheisers and would probably work well for your headphones. I don't hear a lot of difference between the Apple headphone adapter and jdslabs' "Objective DAC". The $10 Apple adapter might even be better than the ODAC, but it only works with my phone. I haven't used Spotify in years; I think I never reinstalled it when my old laptop died in 2018. I could never get past the audio quality of their free tier, and never tried the paid tier. Maybe it's better now. Their recommendations back then for me were really odd; I can understand why some people would complain. I am about the only person that likes Amazon's streaming service but their recommendations are just bland-to-bad. I've noticed Pandora channels have become much more repetitive. Maybe the whole industry has been pushed by their metrics to some horrible least-common-denominator point. There's an argument that discovery is an unsolved problem that doesn't pay. There was a discussion a while back on this here: https://news.ycombinator.com/item?id=29474762 https://news.ycombinator.com/item?id=29474762