Amazon.com: beyerdynamic DT 770 PRO 250 Ohm Over-Ear Studio Headphones in Black. Closed Construction, Wired for Studio use, Ideal for Mixing in The Studio : Musical Instruments
250 Ohm Precision Resistor | Instrumart
beyerdynamic DT-990 Pro 250 Ohm – Thomann United States
Beyerdynamic DT770: EVERYTHING you should know (32, 80, 250 ohms) - YouTube
Metal Oxide Resistor 250 Ohm 5 Watt | Jameco Valuepro
Beyerdynamic DT 770 PRO 250 Ohm | Reverb
Beyerdynamic DT 770 Pro 250 ohm Closed-back Headphones with Calibration Software | Sweetwater
Beyerdynamic DT 770 Pro 250 ohm Closed-back Studio Mixing Headphones | Sweetwater
Got DT 880 250 ohm and can confirm the fact that portable DAC can't drive them at all :) : r/headphones