Originally Posted by manbear
Yeah, but I'm saying bloated bass would correspond to a change in frequency response, right? Unless you're talking about impulse response or some other property?
I don't really understand the science here well enough, but I've seen people who know what they are talking about like Chris J and Steve Eddy argue that damping factor doesn't make a difference for planar magnetics, due the flat, non-inductive impedance curve.
My experience playing around with different resistor values for my speaker amp confirms this, to the extent that my ears are trustworthy, anyway. I definitely don't notice an increase in bass bloat when going from Emotiva with no resistors to Emotiva with 300 ohm resistors (and hence an output impedance of 300 ohms).
I don't see how tube amps come into the picture....
This is because you have a speaker amp...
Planars might not be affected by damping factor because of the flat impedance curve etc, but it is still not ideal to use amps with high output impedance. This is because planar headphones generally being of low impedance need a lot of current to drive them. If you use a high output impedance amp, this will impede the current flow making it harder for the amp to produce the required current before it reaches its voltage limit (and clip).
Where tube amps come into the picture is that many have a high output impedance (OTL ones especially) . If you use a high output impedance amp, you need a very powerful one. This is why the Lyr works well for planars but the Valhalla does not and why your Emotiva works. It won't with lesser amps.