yeah thats why im interested in trying it out.
but its only 15W amp, it'll be nothing into the he-6s 50 ohms, especially since i listen kinda loud and like to raise the volume alot, and sometimes on those quieter recordings, or for bass, the gsx mk2 is good but limited because it still feels like the mids could be better and the treble could be smoother, and that puts out 8w into 50 ohms.
like the F1J that prepro uses, thats only 10W amp, i don't know how much dynamic headroom you will have with one of these.
Per the manual, the maximum unclipped output is +/- 13 V and +/- 2.5 A peak.
If your HE-6 are 50 ohms or so, you will be able to deliver nearly 3.4 Watts into the HE-6. What does that mean for headroom? I'm not sure. Depends on how loud you listen. It may be just fine.
The Headamp GS-X spec says 15 V peak to peak single ended, 30 V peak to peak balanced. That +/- 7 V single ended, +/-15 V balanced. For 50 ohm load that would equate to 1 Watts peak single ended, 4.5 Watts balanced. Although, they spec 1 watt single ended, 2 watts balanced, so there may be a current limit dropping that balanced spec, OR the power specs are RMS, not peak ratings, I can't tell.
In any case, you would have slightly less headroom with the F3 than with the Headamp in balanced configuration.
Hope that helps a bit.