Based on solid reviews everywhere, I bought an HA-1 and have been super happy with it.
I use the unbalanced 1/4" headphone jack to drive Sennheiser HD-580s. I use the balanced headphone jack to drive Audeze LCD-2F. I use the balanced line stage to drive an Adcom 5800 to Magnepan 3.6/R speakers. I use the unbalanced line stage to drive my Tascam digital recorder.
The headphone balanced output runs in pure class A, beefy powerful, with adjustable gain so it can drive almost any headphone. It gets quite warm. The headphone unbalanced output sounds equally clean, though 6 dB quieter (half the voltage, 1/4 the power). The line stage is as impressive as the headphone output. The HA-1 is neutral (neither bright nor warm) and smooth yet detailed. No euphonics, just incredibly detailed yet natural sound for those who want to hear exactly what's in the source without any editorializing.
I would have liked to have had a headphone crossfeed circuit like the ones that Meier amps have, but given all the HA-1's other strengths, I can live without that.
I bought a refurbished unit directly from Oppo. Saved $250 on the price, it looks and runs like new, with same warranty.
Details http://mclements.net/blogWP/index.php/2015/09/06/review-oppo-ha-1/
I use the unbalanced 1/4" headphone jack to drive Sennheiser HD-580s. I use the balanced headphone jack to drive Audeze LCD-2F. I use the balanced line stage to drive an Adcom 5800 to Magnepan 3.6/R speakers. I use the unbalanced line stage to drive my Tascam digital recorder.
The headphone balanced output runs in pure class A, beefy powerful, with adjustable gain so it can drive almost any headphone. It gets quite warm. The headphone unbalanced output sounds equally clean, though 6 dB quieter (half the voltage, 1/4 the power). The line stage is as impressive as the headphone output. The HA-1 is neutral (neither bright nor warm) and smooth yet detailed. No euphonics, just incredibly detailed yet natural sound for those who want to hear exactly what's in the source without any editorializing.
I would have liked to have had a headphone crossfeed circuit like the ones that Meier amps have, but given all the HA-1's other strengths, I can live without that.
I bought a refurbished unit directly from Oppo. Saved $250 on the price, it looks and runs like new, with same warranty.
Details http://mclements.net/blogWP/index.php/2015/09/06/review-oppo-ha-1/