Greetings Traveler! Mobius is an active headphone that contains its own balanced amplifier section, so a headphone amp is not required (or necessarily desired).
Since Mobius has an analog input port, it can technically be used with any source that provides an analog signal. However, use of an amp that provides greater than line level output (such as many headphone amps) can cause clipping, distortion, and possible damage, and is NOT recommended. Excessive power levels can damage Mobius. In AUX/analog mode, do not exceed standard line level voltage to minimize the risk of damage, which is not covered under warranty.
Our recommendation is to use Mobius' USB input direct from your digital device for the best sound, but if you choose to experiment with an external amplifier at your own risk, we recommend exercising caution regarding amplifier volume settings to prevent sending too much power to Mobius' internal amplifier.
Unfortunately there's no formula for determining line level output on a headphone amp. We'd recommend starting with the amp volume at zero, then increasing slowly until things sound good. You can fine tune Mobius' volume control to find the sweet spot for your device. If you hear distortion, just back the volume off on your amp and increase on Mobius to compensate.
Note: If you choose to experiment with other activities, such as skydiving, SCUBA diving or parachuting, please leave Mobius out of it-- unless we're talking virtual activities, then by all means Mobius can help!
If you have any additional questions regarding your Mobius, please peruse the other support articles located in our Help Center. If you cannot find the answer you seek there, please feel free to contact us directly at firstname.lastname@example.org.