I bought an FW1500 a week ago after listening to it at e-earphone Tsutaya, Shibuya, Tokyo, with my Cowon Plenue L. I doubt that you would need a dedicated headphone amp with it, even with the single-ended stock cable, if you have a good enough DAP. The specs are on paper very similar between FW1500 and FW10000, except for sensitivity ( FW1500 is 103db/1mW and FW10000 102db/1mW). Both have 11 mm driver, are rated 6Hz - 52.000 Hz and 16ohm.
I wanted to burn it in with the stock cable first, before starting to experiment with some balanced cables or the Aune B1S amp that I have. I just LOVE the sound and the soundstage of FW1500 – both a huge step up from the FW01 at twice the price. I am pretty sure that the difference between FW1500 and FW10000 is not as big at three times the price. The FW1500 comes with the same case as FW01, except for the logo (His Master's Voice for 1500), so not as great as some Campfire Audio cases and not similar to FW10000, which I still have not managed to see in real life. Until then, I guess I will be very happy with FW1500. If someone living in EU would be interested in a pair of FW01 in "as good as new" condition, let me know. It was JVC's top of the line model until FW10000 (2018) and now its little brother FW1500 (2019) came along.