Pro-Ject 2s Dac vs SMSL M500 (or better alternative)

have you looked at Schiit audio they started making headphone amps with DAC's I've been very happy with my Schiit DAC ( Grungnir MB). they get great reviews so worth looking at.   

https://www.schiit.com/products

Pro-Ject makes DAC's, head phone amps now that's new to me.

I like my Pro-Ject 2S a lot. I use it to listen to MQA streamed from Tidal. No quality issues at all. It's really small though.

But I also like my lil Schiit stack (Modi, Loki, Magni) a lot too. And it has a bit more power to drive my Sennheiser HD650 or MrSpeakers Aeon closed back headphones.

Tidal (or Roon) decodes the first unfold in MQA files. That sounds pretty darn good to me so now I'm having second thoughts about whether I needed an MQA dac at all. 

I bought a used Chord Mojo and that has become my go to dac/amp for headphone listening. The difference, to me, is huge.

So I'm thinking about moving up the Chord line to a Hugo or Hugo2. 

I see Hugo listed here a lot. Right at your price point. Have fun, good luck.