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We don't worry about power, in fact we try to minimize current flow. These days almost everything is designed for maximum voltage transfer. This means you can never deliver more than half the available power, but, it gives you the best shot at minimal frequency response errors, and should create minimal distortion (huge generalizations!) And it is the maximum power you can transfer. This was accomplished by matching the source impedance to the load impedance. In the old days the objective was maximum power transfer. There are two ways to connect two devices. My first instinct was to direct couple the output (no DC blocking capacitor to limit low frequency response), and to make the source impedance as close to zero as possible. Compare that to the month, give or take, that it took to design the input stages, or the week it took to design the power supply. It was one of the most challenging designs I've attempted, and it took a little over six months to complete. I designed a headphone amplifier for a personal mixer system years ago. And that's just on the headphone side of the equation! There are so many factors that come into play, the number of windings on the motor, the wire gauge, the construction of the magnet, and so on. quieter) but that is not always going to be true. The rule of thumb is that a higher impedance headphone will be more difficult to drive (e.g. I would avoid anything lower than about 50 ohms, and anything higher than probably 300-400 ohms, but that is a wild-assed guess. Any reputable music store should do the same. Amazon, among others, will let you return the ones you don't like. The best test is to get both the 80 and 250 ohm models and audition them. TL DR - there is no way to tell from the information available. What the heck does that mean? Without a specification for source impedance it tells us very little. They claim a maximum output of 80 mW into a 600 ohm load. The Apollo Twin specifications are not complete (sad, but common). You are on the right track - you will get better results if you can match headphones to the source.