I bought them a year ago to replace or complement my previous monitor headphones Yamaha HPH-MT220, even though they are in a nearly same price category, which I didn't consider. And I think they sound more or less the same. I might be wrong, but I didn't notice anything new, which is good for me.
Always wanted to try Fostex product and I finally decided to try.
Well, first of all I understand that I need to change the stock ear pads as these are too soft and the drivers nearly rub your ears, which impacts the sound, I'm sure. Didn't try yet, but going to order a pair.
Second, you need a good amp to drive them to their fullest. I bought a USB-powered Fostex HPA4, thinking about a perfect match for them as they are from the same company, but even when setting it to "Hi Gain" mode it seems to struggle to drive them. But! I don't say it doestn't. It sounds way better. But not at fullest even on maximum volume. Mind that.
It's only when I plugged them into my old set of socket-powered DAC+AMP, they sound loud and there's a lot of room for more volume.
If I knew that before, I would have though about buying socket-powered Fostex DAC or had stayed with my old one. Or wouldn't bother with those planar and other hign-impedance headphones.
Other than that, when you drove them, they sound great! Have long seemingly quality cable and looking good quality of materials. Time will tell me that, I've only been using them for a year.