I would wonder why a 60 ohm headphone that needed 100mW of power would be considered hard to drive?
I totally agree and it's the reason for my question. I was trying to avoid naming the headphone to avoid any bias in responses based on its reputation, but that headphone is the HiFiMan Susvara. I recently posted a review describing how I was able to easily drive it to great sound quality from basically every decent headphone amp in my collection.
My challenge is that there are factions in the hobby who are adamant that you can't hear the best of this headphone until it's connected to a powerful speaker amp (such as option 3 in my original post). The argument proposed by this group is that whilst some amps might be quoted to deliver say 2W at 60 ohms, they are actually right at the edge of their performance capabilities and therefore distorting heavily. My response to this is that normal listening levels should require nowhere near those peak levels.
Is there any truth to the idea that a planar magnetic headphone such as this will require significant current capabilities (beyond the sorts of numbers I calculated) to deliver sound effectively across all frequencies at normal listening levels? I can't see the maths suggesting that to be the case and my listening tests align, but it's a hard-held belief and I want to make sure I'm not missing something.
My thinking is this:
- Safe listening levels are around 85dB
- Headphone needs 2mW to achieve 85dB
- A decently powerful amp still has >15dB of headroom even if there are peaks of 90-100dB in the music
- Therefore, power requirements at normal levels really shouldn't be a concern so long as you have greater than a few hundred mW available at 60 ohms and particularly if you have >1W available
The argument goes that these headphones sound fuller and better from more powerful amps. My belief is that they are just hearing the qualities of the amp and attributing it to power rather than amp quality.
Here's a link to my video for reference:
Jump to 11:28 for the discussion of power