There are a multitude of reasons why people want to purchase various DAPs, smartphones, headphones/earphones, amps, and use them single-ended, balanced and the like. All of these choices does not mean that one is better over the other. But to flat out say the boutique DAPs you have mentioned are 'leagues apart' and are 'no competition', that is just a claim that I can not comprehend at all.
It is great that you think your friend's DX50 sounds so much better than any smartphone you have listened to, which means that may very well be a DAP for you to obtain in the future if you are looking for an upgrade from your X1.
So now you say there may not be a huge difference between the X1 and the iPhone 6. I do not think that Dixter was asking you if it was worth getting the X1 over the iPhone 6, as Dixter was wondering if the X1 was even capable of DSD file playback. All that I'm saying is if you are going to claim something, it would be great to have some evidence to back your claims up. To answer your and Dixter's inquiries regarding the X1 DSD playback, the FiiO X1 and the X3 (stock firmware) are not capable of DSD playback, but the X5 is. The X1 supports APE, FLAC, WAV, WMA, AAC, OGG, MP3, MP2 at up to 192kHz/24bits.
If Dixter or you hypothetically asked me if the X1 was worth getting over the iPhone 6, I'm already the wrong person to ask and both of you know my answer by now. There is no DAP out on the market that is over 2 thousand dollars (U.S.) of an improvement over the iPhone 6 or 500 dollars of an improvement for that matter. You'll get much better 'gains' from a balanced amp like the RSA - The Intruder or a superstar DAC/amp like the Hugo. Everything else is supremely subjective, and not worth it for the extra device to pay for and carry (and possibly worry about misplacing/getting stolen) in addition to the smartphone, in my honest opinion.