u/ArgusVolt

Hi everyone,

I’m considering buying a FiiO M21, but I still have a few technical questions before pulling the trigger. I’d really appreciate input from anyone who owns one or has tested it in depth.

1. PEQ and bit-perfect behavior (global vs limited)

Does the M21’s PEQ work system-wide across all apps, or is it limited to specific players like FiiO Music?

Is bit-perfect output preserved when using PEQ?

More importantly: does the PEQ still work when the M21 is used as a USB DAC or as a Bluetooth receiver, or is it bypassed in those modes?

2. Dolby Atmos (Apple Music)

I understand the M21 doesn’t natively support Dolby Atmos in Apple Music.

Can anyone confirm this definitively?

3. Power and headroom for HD560S

The M21 outputs ~720 mW @ 32Ω in portable mode and ~950 mW in desktop mode (balanced).

I’m using Sennheiser HD560S (120Ω), and I also run PEQ with about -5 dB preamp.

I listen to dynamic music (classical, film scores, etc.), so headroom matters.

Questions:

Is the 720 mW (portable mode) enough to drive the HD560S with proper headroom in this scenario?

Or does desktop mode provide a meaningful improvement in dynamics, control, and overall performance?

4. Using M21 with a phone for Dolby Atmos Currently I use a FiiO BTR5 connected to my phone (USB or Bluetooth), and Dolby Atmos (for headphones) works perfectly from Apple Music.

If I connect the M21 to my phone (USB DAC mode or Bluetooth receiver), will Atmos still work the same way (processed on the phone and sent as stereo)?

And in that setup, will the M21’s PEQ still function, or is it bypassed?

Summary of what I’m trying to figure out:

Is PEQ global or app-limited?

Does PEQ work in USB DAC / Bluetooth modes?

No native Atmos on M21, but does it work via external device?

Is portable mode enough for HD560S with EQ, or is desktop mode worth it?

Thanks in advance for any detailed insights — especially from users who have tested these edge cases.

Hey everyone,

I’m pretty new to EQ, so I’d really appreciate some guidance.

I’ve been using the preset for the Sennheiser HD560S, and overall I like the tonality a lot. The only change I made was reducing the 105 Hz band from +5.5 dB to +3 dB, since I felt the original setting was a bit too much for me.

Even with that adjustment, I still find the sound somewhat fatiguing during longer listening sessions. I’m not exactly sure what’s causing it—maybe upper mids or treble—but I don’t yet have the experience to pinpoint it.

Do you have any suggestions on how I could tweak the EQ to make it less fatiguing while keeping the overall balance?

Also, I’m curious about the sound signature of the Sennheiser HD 550. For those who have heard both:

How close can the HD560S get to the HD550 using EQ?

Has anyone tried matching them?

Would you be willing to share an EQ profile that approximates the HD550 on the HD560S?

Thanks in advance for any help!