Hello, I have a technical question about the headphone output of the Luxsin X8 and the relationship between its displayed volume level, gain setting and actual output power. I am currently using a Beyerdynamic DT 770 Pro, 250 Ohm, modified for balanced operation and connected to the balanced 4.4 mm headphone output of the X8. I normally use Low Gain. According to the X8 manual, the balanced headphone output in Low Gain is specified at ≥270 mW per channel into 300 Ohm (9 Vrms). For a 250-Ohm headphone, the corresponding maximum power would therefore be somewhat higher, assuming the amplifier remains essentially voltage-limited at this impedance. 1. What exactly does 0 dB on the X8 volume control represent? If a digital signal reaches 0 dBFS and the X8 volume is set to 0 dB in Low Gain, does the headphone amplifier then provide its full specified Low-Gain output voltage/power? In other words: with a 250-Ohm headphone on the balanced output, can the X8 volume scale be regarded as attenuation relative to the maximum Low-Gain output voltage? 2. Is the displayed volume scale an actual dB attenuation of output voltage? For example, does changing the volume from −30 dB to −40 dB really reduce the output voltage by 10 dB, provided that the digital input signal and all other settings remain unchanged? I am asking because I would like to understand the relationship between digital level (dBFS), X8 volume setting, amplifier gain and the resulting headphone output voltage/power without mixing these different dB references. 3. Finally, I have a safety-related question. Even in Low Gain, the X8 can provide considerably more power into a 250–300 Ohm headphone than is required for normal listening. Under normal operation this is of course not a problem because the volume is strongly attenuated. But does the X8 incorporate any independent hardware or firmware protection against an accidental full-output condition at the headphone socket? For example, is there protection against a volume-control malfunction, software/firmware error, unexpected reset of the attenuation, or another fault that could suddenly cause the headphone amplifier to deliver maximum output? I am not referring to protection of the amplifier or headphones against overcurrent or short circuits, but specifically to protection of the listener against an unintended very high sound level. I would be very interested in a technical explanation from Luxsin regarding these points. Thank you very much.
Regarding the gain settings, the difference between Low Gain and Medium Gain is 2 dB, while the difference between Medium Gain and High Gain is 4 dB. Therefore, the gain setting needs to be taken into account when considering the relationship between the displayed volume level and the final output level. Regarding the volume scale, yes, under the same input signal, gain setting, the displayed volume attenuation corresponds to the actual attenuation of the output voltage in dB. Regarding your last question, the X8 currently does not have a separate protection mechanism specifically designed to protect the listener against an unintended full-output condition caused by a software, or volume-control malfunction. We have also forwarded your concern to our product team. They will evaluate possible solutions and study how this type of protection could be implemented in the future.
