Dac + Amp. Portable. 113dB SINAD for 40$.
https://www.amazon.com/Topping-4330354362-NX1s-Headphone-Amplifier/dp/B0714R3FD9/ref=sr_1_6?dchild=1&m=A2Q0JVLI22BSVA&marketplaceID=ATVPDKIKX0DER&qid=1585958697&s=merchant-items&sr=1-6
Says “AIMPIRE” (Aimpire sells… lo-fi re-branded crap, but “ship and sold by shenzhen audio” ?)
If you want to try tubes, there’s this:
https://www.amazon.com/Little-Bear-Portable-Headphone-Amplifier/dp/B01K4BS9WU/ref=sr_1_106?dchild=1&keywords=dac+amp&qid=1585958350&sr=8-106
If you want to go bluetooth, there’s this:
https://www.amazon.com/EarStudio-ES100-24Bit-High-Resolution-Bluetooth-Unbalanced/dp/B08512RQQQ/ref=sr_1_114?dchild=1&keywords=dac+amp&qid=1585958370&sr=8-114
And the CALs.
https://www.amazon.com/Creative-EF0060-Aurvana-Live-Headphones/dp/B000ZJZ7OA/ref=sr_1_1?dchild=1&keywords=creative+aurvana+live&qid=1585959006&sr=8-1
Just a few ideas of inexpensive hi-fi.
Also: