https://www.amazon.com/Portable-TEMPOTEC-Headphone-Amplifier-Windows/dp/B07D57Z92P/ref=mp_s_a_1_1?ie=UTF8&qid=1548578192&sr=8-1&pi=AC_SX236_SY340_QL65&keywords=tempotec+sonata+hd
Buy the TempoTec Sonata HD, the internals are exactly the same as the other listing, but it's only $20 instead. It's what I use and the sound is fantastic for the price.