“At that point, I started comparing the TA-ZH1ES with the Pass Labs HPA-1 headphone amp, a well-regarded reference that, at $3,500, is considerably more expensive than the Sony. The two amps sounded surprisingly different, though the Sony was richer and fuller, which by contrast made the Pass Labs sound too lean. But, as I continued listening, I felt that the Sony’s honeyed rendering went too far, mellowing out the sound balances of familiar recordings (albeit in a very agreeable way). I came to prefer the more transparent sound of the Sony headphones paired with the Pass Labs amp. Of course, you might go the opposite way and crave the lusher sound of the all-Sony combo; it’s a matter of taste.