I typically recommend Fiio gear for people just getting into higher-end audio. They have some great stuff for <$100 that can be a huge upgrade over smartphone / laptop / desktop output. https://www.fiio.com/amp

I subscribe to this post's message. I was reluctant at first, but after buying a pair of Sennheiser HD650 headphones and a Fiio E10K headphone amp/dac and I can definitely tell the vast improvement in sound clarity.

Fiio's devices are almost there but not quite. I do generally suggest the dx3 because it's a single expense, there's no actual hearable upgrade from it. It measures well and provides enough power for everything short of special cases (such as STAX).