BDP-105 Headphone Amplifier FAQ

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Questions frequently asked at AVSForum about the BDP-105.
The BDP-105 shares the same playback platform as the BDP-103, therefore most questions concerning it that do not revolve around its 'optimized analog audio performance', the 'headphone output' and 'digital coaxial, optical and asynchronous USB inputs' are likely the same as those addressed within the BDP-103 FAQ pages.

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Is the headphone amplifier's dynamic range enough? I usually use volume 20 ~ 30 on my other headphone amp, but need to use volume 80 on the BDP-105.

The BDP-105 headphone amplifier has a great dynamic range. Your volume setting of 80 is actually very good. This is because the built-in headphone amp on the BDP-105 works very differently than other standalone headphone amps.

A standalone headphone amp takes a line-level input signal and amplifies it to drive headphones. Since the input level can vary greatly from one device to another, the amplifier is usually designed to work with a big range of input level. It is possible that when the input level is too high or the volume is set too loud, the output can clip, causing significant distortion. For this reason, standalone headphone amps are normally operated at a low volume control setting (below 50%) to preserve the "headroom" in case a high level signal comes in.

The headphone amp in the BDP-105 is connected directly to the ESS Sabre32 Reference DAC. Its input level is fixed. The highest input level is called 0dBFS and that is the maximum level a digital audio sample can represent. The amplifier is designed to take this 0dBFS input and amplifies it to drive headphone, at the maximum output level (volume control at 100), without clipping.

Volume control in the BDP-105 is implemented in the DAC chip as a 32-bit floating point multiplier. When the volume is set to 100, the digital audio signal is not attenuated at all. The headphone amplifier gets the maximum input level and drives the headphones at the rated output (depending on the impedance of the headphones). If volume level 100 works for your headphones, that's the best. If it is not loud enough (unlikely though), then the headphone amp in the BDP-105 is not suitable for your headphones - you will need to use an external headphone amp.

It is most likely that volume level 100 is too loud. You will need to reduce the volume. Will that hurt the sound quality? The answer is no. Thanks to the 32-bit volume control in the DAC, the performance is as good as an analog volume control but without the statics and wear. ESS has a nice presentation about the volume control mechanism in their DAC chips, which are used in the BDP-105.

The second to last slide says, "A digital volume control with access to the DAC internal data path will behave just like the analog one until it reaches the noise floor of the analog components of the DAC." The noise floor is at -135dB in the ESS Sabre DAC. It is nothing if you reduce the volume 20dB or so, which is volume level 60 on the OPPO BDP-105.

So the conclusion is that the headphone volume level on the BDP-105 is "Bigger is Better". There is no need to worry about the dynamic range or headroom because the headphone amp is a non-clipping design.
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