I reviewed the original FiiO X1 music player in late 2014, but so much as changed in the intervening couple of years, the new X1 2nd Gen now boasts Bluetooth 4.0 wireless tech and a more responsive touch wheel user-interface into a handsome design. Build quality feels more robust, all in all not bad for a $99.99/£99 high-resolution portable music player you can buy on Amazon!
It's pretty tiny, just 2.2 by 3.6 by 0.5 inch (55x97x12mm), and lightweight, a mere 3.6 ounces (102 grams), but the beautifully machined aluminum body feels solid. The X1 second-gen is available in silver, rose gold, or black finishes. The 3.5mm headphone jack can be switched over to line output so you can hook up the player to an audio system, or a set of powered speakers.
The second-gen X1 supports up to 256GB Micro SD cards, but alas, there's no built-in memory. The 1,800mAh lithium-polymer battery provides up to 12 hours of playback time with APE, FLAC, ALAC, WAV, WMA, AAC, and MP3 files, with up to 32-bit/192 kHz resolution. Bluetooth sounded fine over my KEF Muo wireless speaker, but the second-gen X1's menu navigation and user-interface take some getting used to, even then FiiO's isn't all that good.
I started listening to the X1 2nd Gen with a pair of Koss Porta Pro on-ear headphones ($29, £27), and really liked what I heard, the sound was distinctly clearer than what I was getting from my iPhone 6S playing lossless Tidal streaming files. Continuing with a set of 1More Triple Driver in-ear headphones the second-gen X1's transparency advantages over the '6S were even more apparent, though the '6S had a fuller, but muddier sound.
Comparing the original FiiO X1 to the second-gen X1 the sound differences with my NAD HP50 on-ear headphones were more subtle, but I'd still give the edge to the second-gen X1. It really does sound more expensive than you'd guess, at least when it's paired with a first class set of headphones like the HP50s.
If you're looking for audiophile grade sound quality, or just plain better sound than what's available from your smartphone with minimal investment the second-gen FiiO X1 is the way to go.