Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.
I like my 650's. They've got great SQ and detail, and are very comfortable. However, I think that I probably need a better source to really take advantage of them...an external DAC is going to be my next audio purchase.
You can't judge a pair of headphones by their frequency response. There are so many factors that can't be measured by a graph. And, as noted, if you don't plan on getting a source and amp to match, then don't bother.