I've bought creative sound blaster zx today, as I was going through the creative's website, I read in the details for sound blaster ZxR, that with that card you have an option to choose for headphone output impedance between 250/300 and 600 ohms, and there was a warning message there saying that you have to choose 250/300 ohms for the headphones with that impedance and not the 600, because choosing higher impedance for the headphones with the lower impedance can actually harm the headphones, now my questions is, the sound blaster Zx which has a power to drive 600 headphones (I read form unofficial websites) can damage my Sennheiser HD 600 (with 300 ohm impedance) or not, it may seem silly but I am worried, any help would be appreciated, many thanks in advance.
Zx : https://us.creative.com/p/sound-blaster/sound-blaster-zx
ZxR : https://us.creative.com/p/sound-blaster/sound-blaster-zxr
Zx : https://us.creative.com/p/sound-blaster/sound-blaster-zx
ZxR : https://us.creative.com/p/sound-blaster/sound-blaster-zxr