For a flat filter with lowest treble you need 10uf/25v bipolar capacitor parrarel with a 100ohm resistor and both in series with 1.5mh inductor.
Continue in EVO vs red 681. I must say the red 681 is much better in midrange compare to the EVO, it's fuller, smoother and more pleasant to listen to. The EVO has deeper soundstage, better detail, better seperation but the red 681 make me involve more in music with great mid range.
Yep. Female vocals sound much better in HD681. EVO makes everything sexier but it doenst mean it's better. In some disco music EVO is better with fatter bass. I prefer for hard and very punchy bass. But both have quite gloomy bass. Very good punchy bass has Sennheiser HD555 but it was horrible treble and it does not have deep bass.