NiceHCK Octave is a sub-$100 ESS ES9039Q2M dongle that surprised me by sounding more musical than the usual “surgical” Sabre vibe. You get good power (it drove my HD650 fine), a clean background, and strong imaging/separation, plus a companion app with 10-band EQ and firmware updates.
Pros
+Musical-leaning tuning for an ESS Sabre dongle (weighty bass and mids)
+Good technicalities for the price: clean background, solid imaging and separation
+Strong output power (rated 550mW @ 32 ohms on 4.4mm) and drove my HD650
+Tactile, satisfying buttons and gain switch
+Companion app with 10-band EQ and firmware updates