Originally Posted by schaqfu
Wow, good stuff. Haven't seen this explanation before.
So if the damping factor is 10 coming straight out of the balanced line output to the HD650s, and it's 2727 coming out of the headphone jack, how and why is it that so many people are reporting significant improvement in quality when going through the balanced outs from the DAC1 directly to their HD650s? Virtually everyone reports significant improvements in bass handling, tightness and articulation -- all the things one would typically expect from a balanced amp versus unbalanced.
Why are the numbers lying?
There was a comment I read by Andrea Ciuffoli in an this tube amp design
|My first test was done with the E182CC (figure 1), but there is the limitation on the usable impedance of headphones in the range of 300 to 600 ohms for maximum performance. The output impedance of the amplifier is about 35 ohms, and I don't accept any damping factor less than 8. (About damping factor: for some, a damping factor of 4 or less is acceptable, but only because they have not heard a better tube headphone amplifier like this one.)
So a tube amp user/designer doesn't expect a damping factor of < 8, which is less still than our theoretical 10 above.
I wonder if people are used to low damping factor from decade of slack equipment. I wonder if the tightness and very short decay of the bass with 300Ω loads from the DAC1 is what makes it 'too clinical' to some people.
My theory: when you take the lines off the back of the DAC1 and run them through your balanced headphones, the damping factor returns to something the average user thinks is correct and is thus better to them.
Can we get the output impedance specs for a balanced headphone amp? There's some for the Rudistor NX-33, but it says 0.1-1200Ω which I think means that's what the amp can drive, not the actual impedance of the amp itself.
This is a very interesting discussion, let's keep it up!