Superlux HD668B　EQを設定すれば数十万円のヘッドホン以上の音質
Equalizer APO設定
Preamp: -8.5 dB
Filter 1: ON LS Fc 30 Hz Gain 4.0 dB Q 1.0
Filter 2: ON LS Fc 50 Hz Gain 4.0 dB Q 1.0
Filter 3: ON PK Fc 4000 Hz Gain 5.0 dB Q 2.0
Filter 4: ON PK Fc 5380 Hz Gain -7.0 dB Q 6.0
Filter 5: ON PK Fc 8582 Hz Gain -7.0 dB Q 5.0