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Originally Posted by dspargo
 He says in a recent post:
The DAC1/USB/PRE does, in fact, have true-balanced outputs. These outputs can drive balanced headphones. However, I strongly advise against this configuration using any balanced headphone amplifier. Also, from the link above: Balanced headphone amps will double the source impedance of an unbalanced headphone amp. No matter how low the impedance of a balanced headphone amp, it could be half that much if it was unbalanced. This is one reason balanced headphone amps are not a good idea. (It should also be noted that the balanced output of the DAC1 / USB / PRE is 60 ohms or greater, depending on the attenuator settings). Not only will the source impedance double with balanced headphone amplifiers, but the total distortion and noise of the amplifier will double as well!! Every output device (opamp, transistor, tube) creates some distortion and some noise. If there are two opamps or transistors or tubes driving each headphone speaker, twice as much distortion and noise will be added!! |
I'll tread lightly here... After a quick discussion with our audio engineers, we simply do not agree that balanced amps are inherently noisier or have higher distortion artifacts than identical single-ended designs. In fact, our single-ended units actually have identical THD figures [at 1v output] to our balanced rigs, <.002% ... Moreover, the output impedance simply does not double. In fact, our single-ended rigs have output impedance [at 1kHz] of 0.5 ohms; the same exact balanced rig rises to 0.6 ohms.
Finally, keep in mind that the inverse relationship between positive/negative in a balanced head-amp allows for near-total cancellation of many line-level anomalies & background noise floor issues too which, of course, helps to make the music erupt from much "blacker", quieter background than is typically possible with standard single-ended rigs. There is no true “ground” with balanced headphone systems, so there is really no opportunity for the crosstalk /distortion issues described above to occur ... and the resulting doubling of a balanced amp's voltage swing makes for some extremely liquid-quick dynamics and precise musical detail resolution to boot!
This balanced-drive HeadRoom topic is much better explained in some detail at our website under the 'Product Resources' > 'About Balanced Headphones' link.
Products - HeadRoom - Right Between Your Ears
Cheers,
Jorge
HR Sales/Product Manager
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