@Rodolfo if you have the time and energy, could you give a bit more detail about your FiiO M21 please? You use the same sources as me so I'm interested to understand things like:
- How easy is it to add / remove tracks / playlists / albums from the TIDAL and Spotify apps?
- How much space is the average lossless album / track taking up? I'm keen to know just how much music these things can store on a 2TB card. I'm pretty sure it'll be way beyond what most people need but I have no idea how much space a lossless track takes up, so it'd be good to get an idea
- Any other impressions you have about things like general usability, sound quality, battery longevity and what headphones / IEMs you've used with it
- Most important of all - have you paid for the extra gimicky Walkman-style case?
Surely, as I am able:
1. I don't use either, although I did subscribe to Spotify before its podcast-priority re-direction/-investment: I subscribe to Amazon, and I only stream its albums and playlists. I'd expect that one could do these things (only) as well as on any DAP. There is an M21 thread at the head-fi.org forum where you may read-up or inquire on this Q.
2. I can summarize/ballpark it this way: I have about 1100 albums that include 13,661 tracks. Virtually all of my Jazz and Classical -about 50% of the total- are ripped in FLAC (mostly) or WMA lossless (FLAC is more efficient, but I like them both). The current total takes up 233GB and I can still fit it in 256GB cards. These stats are from my MusicBee program, with which I've ripped and managed my collection for about a decade.
3. I have two other (more compact) HiBy DAPS that I still mostly use. The M21 is special in that it has a Desktop mode that generates a signal that through an input in my Rotel A12, makes my system perform/sound magnificently. This unit is equipped with TWO USB-C ports and the mode involves connecting the M21 also/simultaneously to a power supply through the second/input USB-C port so that the device's amplifier/componentry is fully dedicated to OUTPUT through the primary USB-C port. This mode is all cabled/wired and I use my hi-fi as I normally do but specifically through the PC-USB input to access the M21 as the source. (That writing can surely be improved.) I do also use the same head and earphones that I use on everything else which means two Sennheiser HD598s (with balanced cables), a Sony 7506 (c. balanced connector?), Bluetooth Soundcore Q35, Fiio FH3 earphones, and most recently, the Fiio FT1 Pro. They all sound great through the M21, though not especially greater than they do through my other DAPS, my hi-fi, or a Fiio K11 which I was first trying/testing this weekend. CERTAINLY, for me, it is the Desktop mode that distinguishes the M21 in my hi-fi practice, and without which I probably would not have kept it. I will add that it is now/definitely my best DAP and the one I'd keep if I had to keep only one. I also trialed the also-android Class-A amp-equipped HiBy R4, but I returned that because it is less-pretty, a little heavier, and did not bowl me over like the M21's desktop mode, but now I'm repeating myself. Absent you know what, I probably would have kept the R4 (because I did require an Android DAP for Amazon music that also had a USB-out for my hi-fi -which I've had -sans Amazon streaming- with one of my HiBy DAPs for years). I also returned the thus-satisfactory, technically- and cost-impressive, but too-plasticky Fiio/Jade Audio JM21, by the by.
4. I am fully-satisfied with the tight-fitting and light silicone case in which the M21 arrived. It's not as impressive as the very nice leather case included with the HiBy R5 II, but that was several years ago, and I returned that one too. I have had zero interest in the gimmicky-indeed cassette simulation case since I first saw the M21 advertised -although I do admire that Fiio is playing and offering this inexpensive and creative but totally-optional way to play with this player. Note that that optional case does have some limits on the control of and access to the M21.
I'd be glad to clarify or elaborate as you like and as I am able.