There are numerous variables in play here, but perhaps the most significant question is if using your iPad as a source device maintains a bit perfect audio stream to the USB output. Interestingly enough, I believe there may an issue streaming Apple Music, but what I find in a quick search implies that third party (e.g. Spotify, Tidal, etc.) content comes through unmolested (ie. not resampled by iOS).
Inexpensive streamers (e.g. WiiM) bring a one-stop shop of features and conveniences that satisfy most consumers. More expensive streamers bring lower noise power supplies, more precise clocks, and more expensive integrated DAC platforms that appeal to discriminating consumers. You already have a standalone Chord Qutest DAC, so no reason to spend on an integrated DAC that you won’t use. Your Chord Qutest DAC has galvanically isolated USB implementation that minimizes electronic noise generated by your iPad and is the preferred connection. With asynchronous USB, your Qutest DAC (not source device) has the master clock, which is plenty good for your Spotify streaming.
The important caveat here is if you use your iPad for volume control, it is doing this in the digital domain and adversely impacts dynamic range. If you have a means of controlling volume in the analog domain (post DAC), that is the preferable route. For best results, you would set your iPad volume around 95% of maximum and control system volume at the preamp or amp.
