senorx12562
500+ Head-Fier
Here's the thing. While high impedance (like 250-300 ohms) make a set of cans harder to drive to a particular volume, they also present an easier load to the amplifier. Planar magnetic drivers in general tend to be low impedance/low sensitivity, (iirc, Sundara are like 37 ohm, 94db sensitivity, while my hd6xx are 300 ohm, and like 103db sensitivity and are a much easier load for an amp. With most amps, the higher impedance means the cans are seeing much less power at a given volume level. They end up at similar volumes at similar volume settings, but because of the lower impedance the Sundaras are seeing way more power (wattage). If the hd6xx was seeing the same amount of power it would be unbearably loud. I'm sure this is an oversimplification, and my understanding could be totally wrong. Wouldn't be the first time. When I was looking at the Sundaras, I knew hfm was full of schiit when they said they were suitable for use with a phone, so I wasn't surprised. I never use them away from home, so it isn't a big deal that they aren't great with a dongle. I think many planar cans are much worse though.When you first posted about your Sundara´s not being driven adequately I found it hard to believe, and reading you post about it again made me rethink so I went to the Sundara thread, and there are people in it saying a THX Onyx drives them well, whilst others say they need power (one or two watts minimum) and others are driving them out of their amplifiers´ speaker terminals which honestly felt like "Susvara Reloaded" and made me stop reading. I won´t doubt what you´re experiencing but if a €349 headphone needs that much power to sound properly something ain´t right over at Hifiman.