I'm in a position to consider a purchase of a new DAP as well. Here are my criterias:
1. Digital transport only. Never felt that I can get enough power and drive from a DAP alone. If it was a light travel day I'd be with my WS99BT or B&W P5 Wireless and AptX it with my S6 Edge.
2. Large enough storage. Herein lies the dilemma. DAPs with dual storage slots like X5ii aren't Tidal-friendly (which will be my 3rd criteria later). Although storage problem will be solvable with swapping microSDXC cards (when are the 200GB microSDXC getting here la?), that is not really ideal.
3. Tidal-friendly. That covers Qobuz too if or should I decide to splurge on that. Therefore the DAP must be able to install the Tidal app. Hence either iOS or Android only. Unless you go desktop route, which what I am doing with my 2015 MacBook and Chord Hugo.
4.. Minimum 24bit/384khz, DSD for future-proofing(somewhat). I could live with 24bit/192khz, since that's where highest quality of the content I listen to is at. Therefore requires data stream to the DAC after playback decode on the DAP to the DAC at those quality rates, via whatever connection that it has (coaxial, SPDIF or USB).
With these criterias, the DAP only works as digital transport, therefore the bigger storage size it is, the better. And please no clunky UI bullshit like in the Lotoo PAW or its equivalent, no matter how godly the DAP's sound processing or amplification circuitry is, it's useless since the DAP will be digital transport only. The DAP fucntion is to display the UI smooth enough, and to process, decode and play the files of the quality mentioned above, pass those signal to the DAC (Chord Hugo) via SPDIF, coaxial or USB.
With all those said, I believe my option has been reduced to either Android smartphones with USB OTG function, iOS device with Onkyo HF player (can decode and play up to DSD via PCM conversion), or hybrid DAPs with Android functionality(to be able to install Tidal, Spotify, Qobuz app) such as the Sony ZX1 or ZX2. Am I correct to assume this?
I'm sure if I eliminated the need to Tidal, my options are wider open than it is now, but I use Tidal (and to a certain smaller extent, Apple Music) to discover new music and new artists. Don't get me wrong, there are artists who are my staple diet in music, I cant live without Charles Mingus, Ella Fitzgerald and Diana Krall, but I like the new upcoming ones like Ed Sheeran and Charlie Puth as well, and would not have discovered them without Tidal or Apple Music.
So, are my choices limited to Sony ZX1/ZX2, iOS devices (iPhones, iPads, iPod Touch) and <insert whatever Android smartphones here>? I've just tested my S6 Edge--> Chord Hugo, works fine but damn crackly and noisy unless I turn on airplane mode. No such crackle and fuzz with my iPhone 6 Plus. And then there is the problem of storage. Which I foresee will never be enough with the burgeoning filesize of HiRes content. Hence why I see Tidal being the solution.
Even just use the player as digital transport, sound quality and signature might be different also.
I've tried the coaxial output of Fiio X5ii, iBasso DX90 and Cayin N6, the difference is quite obvious.
Not really recommend Andoird phone + OTG. Sound quality is not up to audiophile level. A HiFi quality OTG cable is difficult to find also.
X5ii and N6 both can support DSD natively, but it will convert to PCM format (normally is 88kHz/ 24bit) when using coxial output.
Most of the digital transport and DAC can only transfer or receive PCM signal via coaxial.
If you can accept desktop unit, Oppo 103 / 105D will be a good choice. They support Tidal and Youtube. Also support SACD/ CD/ DVD/ Blue-ray. Can connect to USB thumb drive or hard disk, then use iPad/iPhone or Android device to control and select music.