Pros: Opus and WavPack support, ultra low consumption, excellent sound, small footprint, packed with advanced/geeky features, EQ (!!!), speed control
Cons: Not suitable for ultra sensitive IEMs due to slightly elevated noise floor, sub-optimal crosstalk performance into 16Ohm and THD+N
The following review considers Clip+ with one of the latest Rockbox builds. Any features mentioned therein are from Rockbox frontend, not Sansa.
Clip+ won my annual price for the most influential product of 2016 in price/value ratio. Granted, it was released in 2009, but finally I got it last year, and it was instant winner, topping even the most awesome buy of AKG K240DF.
At first I needed something to replace the aging SX480 CD player, which still does work, but I'm not that avid "CD burner" nowadays. Fiio DAPs are just too heavy and large to be convenient for portable operation, so I opted for Clip+, despite the reports of CPU chirping in the headphone out (which none of my units experience).
Yet Clip+ managed to overthrow one DAP after another. In the end, I kept only Clip+ and I couldn't be happier with it.
So how did that happen?
Firstly Clip+ boasts with higher-than-average battery runtime of 20 hours. With special beta Rockbox, it's possible to get even 30 hours when playing back FLAC at 44.1kHz. Both my Fiios (X3II and X5II) top at 12 hours max. To get more, power banks need to be introduced, which increase weight and size, pushing them into "transportable" category, rather than "portable".
When Clip+ arrived at the scene, naturally the first thing to do was listening and comparison test. I compared Clip+ to X3II and X5II very extensively for over 2 months and found no verifiable improvement in sound, not any that would justify the extra price or power consumption. As I'm no placebophile and focus on more "down-to-earth" features than fantasy-like promises of "better sound" at all costs, suddenly Fiios lost precious ground. There are still reasons to keep them (DAC functionality, DSD, automatic sample rate switching), though not for the majority of uses.
I desperately wanted WavPack and Ogg-Opus since 2015 and Clip+ delivered in full and also added IT, S3M, XM, MOD module support and MIDI playback with its own soundfont. No other DAP regardless of price (yes even HM-901), at least those I checked, come with Opus support.
To those who don't know what's Opus - it's lossy, compressed format, currently with the best compression vs. quality ratio. Even 128kbps sounds incredibly transparent. Usually only vocals give it up.
Clip+ unlike other "high-end" DAPs also comes with advanced features such as crossfeed, HAAS virtual surround, speed control, 10 band equalizer with adjustable Q, channel operations, ReplayGain, time-stretching and onboard compressor/limiter. Constructing playlists on the go is super easy, and they're stored in m3u8, thus fully compatible with WinAMP or Foobar2000.
There's 100% true gapless playback on all its supported audio formats, except modules. Where Fiio would pop during track change (lossy formats), Clip+ jumps to next track without any sound.
And for good measure, voice and FM recorder is included too. Built-in microphone is no high-class, but it's easily replaceable for say Primo EM184 or EM258. Both achieve good clarity for voice recording and even some music. Clip+ offers lossless formats for recordings, including WavPack.
Where Clip+ slightly lacks, that'd be the department of power. Both Fiios achieve over 100mW figures into low impedance loads and very impressive voltages for DAPs.
2.67Vrms for X3II and 2.82Vrms for X5II. Clip+ runs at 0.82Vrms maximum - all figures are into unloaded output (5MOhm).
However considering that Clip+ amp stage, integrated into its SOC, together with DAC, runs for couple miliwatts, that's fully understandable. In another words, Fiios consume over 40 times more power.
There are likely more features I have unintentionally left out, but for me, the Clip+ is the best DAP I have ever owned, hands down. If you don't have it, you can still get refurbished unit, just like I did for about $60 for 8GB model.