I'm just trying to find the best amp/DAC for $300 or less .
Also amp / dac that can drive the hifiman he 500 s
I've run my HE500's off several devices and you can get by on this budget very easily.
NFB12, NFB11.32 or NFB15.32 should all be in this price range and provide the most power for your money, while still having a good DAC and filters and options combined. Best per buck for features and power really.
Schiit Modi & Magni can do it just fine. Also, the Asgard 2 with Modi as an option (would be slightly better).
JDS Labs O2 and (ODAC or any other DAC) also handle it fine.
You can find the discontinued NFB12 usually for $120~150. It's every bit as good as the $300 ones. Provides greater than 2+ watts into 38ohms, powers Orthos very nicely, and has a good DAC. Lots of digital connections, and gain options. Very well rounded all-in-one for a stupid price. I would take it over the Modi/Magni if you can find one local/used.