To measured the performance of the Pro 500, I used a G.R.A.S. 43AG ear/cheek simulator, a Clio FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and the Musical Fidelity V-Can headphone amplifier. Measurements were calibrated for ear reference point (ERP), roughly the point in space where your palm intersects with the axis of your ear canal when you press your hand against your ear. I experimented with the position of the earpads by moving them around slightly on the ear/cheek simulator, and settled on the positions that gave the most representative results and the best bass response.
The Pro 500’s frequency response doesn’t show as big a bass bump as our listening tests suggested, but maybe that big dip in the midrange, centered at about 500 Hz, is subjectively creating the impression of big bass. Adding 70 ohms output impedance to the V-Can’s 5-ohm output impedance to simulate the effects of using a typical low-quality headphone amp has raises the bass response by about 0.5 dB and lowers the treble response accordingly—subtle effects, but probably audible.
Total harmonic distortion (THD) at 100 dBA is low above 100 Hz, but rises in the bass to about 8.5% at 20 Hz. Isolation is about average for a large over-ear model: nothing in the bass, -10 dB at 1 kHz, dropping to -25 dB or so at high frequencies.
Measured impedance averages 21 ohms. Average sensitivity with a 1 mW signal at 23 ohms rated impedance is 104.1 dB from 300 Hz to 6 kHz.
The Pro 500 is a beautifully, bodaciously styled headphone with a unique sound. In the mids and treble, it reminded us of one of Grado’s audiophile headphones, which have a rep for fantastic detail but thin sound. In the bass, it reminded us a bit of some of the hip-hop headphones we’ve heard; although the bass wasn’t quite Beats-big, it was clearly intended for those who like plenty of bottom end. For the right person, this is an extraordinary headphone, but make sure you’re that right person.
Brent Butterworth and Geoff Morrison combine their years of gear testing and knowledge in one überblog of irreverence and techiness.