Despite my posts being so enthusiastic about the W2 I really was skeptical that it would be better than the portable USB DACs I had collected over the last couple of years. In fairness, I never bought the higher end, but rather collected the mid-tier (xDSD, NX4 DSD, DF Cobalt, Monolith THX portable, Micro iDSD BL) but I spent today comparing those DACs connected to my iPad Pro 12.9” 2020 (USB-C) with the W2 (using IER-Z1R for all).
***The W2 was the best sounding DAC***
Seriously. No question for me IMHO. I played Redbook and MQA via TIDAL; I played Hi-Res up to 192kHz via Qobuz. The W2 out-performed my battery-powered external DACs. I can’t see a reason to ever use those DACs again on the iPad when this dongle sounds better, and due to its size and lack of a battery, is way more convenient. I had more volume range on the W2 too.
Now, my portable DAC/Amps don‘t have the power of a C9 or Diablo, so volume range isn’t really a useful metric. But pure sound quality is, and the W2 sounded better than all my DACs connected to the same source with the same headphones. I still don‘t fully believe it: how can something this small with no battery power sound this good and this powerful? This is the future for IEM users, not the C9. You don’t need more amplification for IEMs than what the W2 provides. [Caveat: the C9 can bring some tube magic to the equation though if that’s your thing.]
I also have 2 DAPs, Sony ZX507 and FiiO M11 Pro (again, mid-tier, not high-end DAPs), that I compared to the W2/iPad combo. Note: UAPP recently released an update that allows the ZX507 to play bit-perfect* out to the proprietary Sony DAC (*almost: it zero-pads everything to 32bit but honors the sample rate). The M11 Pro allows bit-perfect for 3rd-party apps since a couple of firmware updates ago.
In summary, the W2/iPad combo was better than the ZX507, but the M11 Pro was equal in performance to the W2/iPad. I should note that this is typical for the ZX507: 3rd-party app performance does not sound as good as it‘s native Walkman Music player app. So, my caveat is I played locally stored FLAC on the native ZX507 app vs streamed music on the iPad/W2 setup and the Sony local playback was unsurprisingly better (Sony apps with locally stored music is hard to beat on any Sony DAP).
TLDR and jumped to the end: this W2 (connected to an iPad Pro 12.9” 2020 USB-C connection [no lightning connections here]) was really awesome compared to some mid-tire USB DACs I own.