Re: Samson SR850 and Superlux HD668B
Having owned both, here are my thoughts about them:
Although they are very similar in sound they're not identical.
The main difference between them is in the bass region, where the Samson's are more extended and have significantly more impact than HD668B does (which can get boring at times).
There are also differences in the high end of the spectrum which I cannot be sure of 100% (I've only had both for a few days, before selling the hd668 and keepind the sr850).
It could be that the richer bass of the Samsons make them sound a bit more balanced and less etched, but it can also be that they simply have a flatter treble response. I don't know.
In terms of detail, imaging and tonal accuracy I think they're too close to choose a winner.