You might find the Topping DX3 Pro+ is a good fit for your requirements. At 4.75 X 1.25 X 5.5" it's pretty compact, it uses a decent ESS ES9038Q2M DAC chip and supports coax and optical inputs up to 768/32 and USB up to DSD512; and Bluetooth 5.0 with LDAC and aptX HD. As a headphone amp, it delivers 1800mW into 32 Ohms, meaning it will drive just about any dynamic headphone with lots of headroom - including my notably inefficient HiFiMan Sundaras - with a very quiet, detailed, clear and neutral signature. Setup-wise, it offer 7 different rolloff filters, and +6 or +19dB HP amp gain, for starters. And it comes with a nice big display and a remote. That it does all this for under $200 is quite an accomplishment.