When I had the Headroom micro DAC/AMP combo with the desktop DAC chip I noticed that my Grados from the SR60, SR80, SR225, and RS1s were particularly bright and very fatiguing. I even had a chance to listen to a HR Max DAC/Amp with my Grados and it was very fatiguing as well . I did notice that they performed well with the HD650s and K701s though.