Yes, I have. I've been using The Fosgate with Hifiman Edition X's and they sounded wonderful together. A month or so ago the plastic headband on the X's broke and I could'nt fix it. I bought a refurbished HE1000se from Hifiman and that's when I found out the Fosgate was underpowered. Not that they sounded bad together, they did'nt, the HE's just lost some of the dynamics that the X's had. The Fosgate makes 1 watt (1000 milliwatts) at 32 ohms and that's not enough for the HE's. I bought a SS SMSL H400 amp that puts out 7 high current watts at 32 ohms . That should wake up the HE's, I'll find out Monday when the amp get's here.
Hopefully I can find a replacement headband for the X's as they are remarkable cans. I'm going to keep the Fosgate as it's a killer amp with the right match. I bought (stole) it used about 8 or 9 years ago from a guy who was getting divorced for $150.00. Still can't believe my luck. I've never seen another one for sale anywhere. I've seen the phono preamp but never the headphone amp.
Regards,
Sam