Hello QQQ. I'm well aware of the concepts concerning damping factor as applied to loudspeakers, and it's really no different with headphones. It's still largely irrelevant to a degree, if not even more so. There should be little effect on the frequency response or dynamic behavior, especially since there's no enclosure (HD600 is even an open headphone) or heavy cones to control. Seems as though his sound card is heavily promoted for headphone use, claims to work fine with headphones of 32~600 ohms, but obviously doesn't mention power output capabilities. Does anyone have a schematic? It's likely not the most powerful thing on earth, but I'm sure it's fine. Regardless, there's no amplifier that's going to significantly raise the low end below resonance. Also, altho Fs is around 100 Hz (typical), the roll off is actually fairly shallow -only between first and second order (it's actually still less than 10dB/oct after the knee), due to the open back design. The Qt of the driver obviously isn't INSANELY high (like a lot of headphones I've come across tend to be). Therefore, these drivers obviously have a sufficient motor structure, low freq damping is not only fine, but very good. Their resonance is just a little too high for equal output below 60 Hz or so, that's all.. and this is the usual for headphone drivers. A lower resonance would only take away from sensitivity, and efficiency would be even lower than it already is. So, if that were the case, everybody would be griping about that instead.. which is why a large portion of headphones are typically somewhat limited in low bass resposne. The only reasonable solution to this is EQ'ing the low end a bit. Even a software eq can work just fine, however, the downside to all of this (especially with any sort of digital EQ), is that you'll have to prevent clipping.. likely your sound card, if that's what you're using with these headphones. Therefore, you'll need to significantly lower the over all volume while adding the eq. This can be an issue if your amplifier doesn't have a fairly significant amount of headroom for the needed gain. taso89: What software are you using for playing your music? Can you use VST plugins with it? See my screenshot below, I just added this to my HD600's using foobar2k. Works great, and it's the only real possible solution..