Headphone Amps

A/B Comparison #2

• Sigma 22 power supply.
• Three-channel "Active Ground" topology.
• See http://www.amb.org/audio/beta22/

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LCD-2:  

Very hard to tell the difference.  Both amps sounded great.

Sennheiser HD-800:

Audible differences but VERY slight. The bass on the Beta-22 had more weight, seemed to go a little deeper. Highs on the Beta-22 sounded just a tiny bit cleaner.  Depth of soundfield, midrange clarity, etc., no differences heard. CK²III had a tiny bit of AC hum audible when the music was paused.  Hard to hear, at the very borderline of inaudibility, but present.  (Actually quieter than the hum from my refrigerator two rooms away as heard through the open-air Sennheisers... I had to take some pretty serious measures to get dead silence in the room I was in to hear it.)

CONCLUSIONS:  

1. I REALLY expected to hear MAJOR sonic differences here. But that was NOT the case, such differences as I could hear were very subtle.

2. I found it SUPER important to get REALLY close level matching between the amps.  I perceived any tiny difference in level as a difference in QUALITY, and NOT as a difference in level!  So I matched the output across the headphone in test using a VOLTMETER to within .005 volts RMS for both amps.

3. As with the first round of A / B comparisons, these are BOTH great amps, and they BOTH sounded beautiful on these two world-class headphones.  I had a slight preference for the Beta 22, especially on the HD800's.

4. The Sennheisers seem to be more sensitive to the type of amp used, whereas the LCD-2's seem much less picky about amps.