linerrorUsing the sub out would make more sense. There's no crossover, so unless it's mono, it's essentially a preout. One of the few downsides of this device, which is an upside in this bizarre use case, is that the sub out is still outputting when plugging in headphones.
linerrorWhy wouldn't you? I have JBL monitors (MD flavored series 3XX) and run them through a dac/amp unit. Yes the speakers are powered but that doesn't prevent them from benefiting from the DAC circuit. My unit has separate preamp outs where this one doesn't seem to, but I'm guessing the manual covers that connection. The other nice features offered are obviously the bluetooth connection and the remote control--I wish I had both on my Jotunheim!
Yigal.Kit is mono, or summed. per Topping support. "Your MX3 is normal. We do this is because some users will use MX3 as a pre-amplifier, they will connect the power amplifier from the headphone jack, and they need subwoofer output at the same time. So if you need to use headphone only, please pull out the subwoofer output."