How should I use Mojo 2's EQ, and is it really lossless?

The practical answer

Use Mojo 2's EQ for broad adjustments: weak bass, a bright headphone, sibilance. In January 2022 Watts wrote that it "is not parametric DSP, but a broad brush way of tuning the sound quality balance" Head-Fi, Jan 2022, and in February 2022 that it is not meant for sharp headphone resonances Head-Fi, Feb 2022. He calls it lossless in the sense of transparent, not bit perfect Head-Fi, Sep 2023.

What the controls are

In January 2022 he listed a 20 Hz peak (boost or cut up to 9 dB), a bass shelf from 125 Hz down to DC (plus or minus 9 dB), a treble shelf from 3 kHz up, and a 20 kHz peak (plus or minus 9 dB) Darko.Audio 39:52. Those ranges come, so check the recording. The peak filters have a Q of 0.5: with 20 kHz at minus 9 dB, 10 kHz is minus 4.5 dB Head-Fi, Feb 2022. One step on the volume or tone controls is 1 dB Head-Fi, Apr 2022.

How he says to use it

Intent. In February 2022 he gave two purposes: compensating low-frequency problems in headphones and IEMs, and adjusting balance to taste Head-Fi, Feb 2022. At the CanJam NYC seminar in late February 2022 (video published March 2022) he said that if you have a 6 kHz resonance to null out, "forget it" MFG Audio Reviews 40:53. He also wrote that EQ can't cure brightness caused by distortion or noise floor modulation Head-Fi, Jan 2022.

Warmer sound. In January 2022, asked how to make Mojo 2 sound more like the original Mojo, he suggested the shelf up a couple of dB and 20 Hz up about 1 dB Darko.Audio 43:03. In February 2022 he wrote that boosting the bass shelf a few dB gives Mojo's tonal impression Head-Fi, Feb 2022; in March 2022, that no setting precisely replicates Mojo Head-Fi, Mar 2022.

Sibilance. Drop the treble shelf by 2 or 3 dB (January 2022) Darko.Audio 42:13.

His own settings. In May 2022 he said he had "no great need to EQ my DCA Stealth" Head-Fi, May 2022. In May 2023 he wrote: "I use my DCA Stealth and set the bass shelf EQ to +3 or sometimes +4", other bands at 0 Head-Fi, May 2023; in July 2023, +3 dB on the 125 Hz shelf Head-Fi, Jul 2023. In a video published March 2026 (recording date not stated) he said he always uses it, particularly when flying Audio Force 36:34.

Reset, saving and volume

Reset. In March 2023 he quoted the handbook: + and - pressed together in the DSP or crossfeed menu restores DSP flat and crossfeed off; he chose not to add a separate EQ on/off option Head-Fi, Mar 2023.

EQ off. With EQ and crossfeed off, the volume control receives bit perfect data (February 2022) Head-Fi, Feb 2022.

Boosts and clipping. The volume control is the last stage, so a boost may mean reducing volume (February 2022) Head-Fi, Feb 2022. In December 2024: "if you added +3dB via the EQ then you would need to go 3 steps down to guarantee no clipping with 0dB FS input signals" Head-Fi, Dec 2024.

Saving. In September 2024 he said settings are written to flash once the menu returns to default after 8 seconds without changes, so changes made without waiting are lost Head-Fi, Sep 2024.

4.4 mm version. In the same video, published March 2026, he said the 4.4 mm output remembers its own volume and EQ settings, separate from the 3.5 mm output Audio Force 33:44.

Is it really lossless?

His definition: "perfectly transparent, or what I have called loss-less - so the EQ makes the required changes without degrading subjective performance" Head-Fi, Sep 2023. He says conventional EQ throws away tiny signals and its floating point makes things harder and brighter; Mojo 2 uses a custom 104-bit fixed-point core at 705/768 kHz with each node noise shaped, so small signals are never lost, which is why he used the term Head-Fi, Sep 2023. His test compares a 6 kHz signal at -301.030 dB against 0 dBFS to within 0.001 dB and 0.001 degree; the claim that such errors are audible rests on his own listening tests Head-Fi, Sep 2023. In June 2024 he called the UHD DSP "subjectively loss-less" because switching its HF filter in and out was inaudible Head-Fi, Jun 2024. In an interview published February 2025 (probably recorded at a Munich show in May 2024; unverified) he said EQ on it does not change sound stage or depth audio-2G 18:39, and in the video published March 2026 that normal EQ "seriously damages sound quality and musicality" Audio Force 36:34.

DSD is converted to 705.6 kHz PCM and fed to the same DSP, so EQ works identically (February 2022) Head-Fi, Feb 2022. He advises not letting the source apply EQ, volume or upsampling to his DACs (November 2024) Head-Fi, Nov 2024.

What he has not said

Beyond his own DCA Stealth settings, the archive has no recommended settings for particular headphones and no independent measurements of the EQ Head-Fi, May 2023. In March 2024 he said Quartet would have "more complex and lossless EQ" Head-Fi, Mar 2024, so Mojo 2's controls do not describe it.

Quotes

“no EQ is bit perfect, as that implies that nothing is being changed to the bits, so EQ wouldn't actually have any effect.”2023-09-14 Head-Fi, Sep 2023

“Note that the DSP is not parametric DSP, but a broad brush way of tuning the sound quality balance.”2022-01-31 Head-Fi, Jan 2022

“It's not intended to solve headphone HF problems, as these tend to be sharper resonances.”2022-02-03 Head-Fi, Feb 2022

“I use my DCA Stealth and set the bass shelf EQ to +3 or sometimes +4.”2023-05-30 Head-Fi, May 2023

“if you added +3dB via the EQ then you would need to go 3 steps down to guarantee no clipping with 0dB FS input signals”2024-12-11 Head-Fi, Dec 2024

Dated positions

Caveats and open points

• The lossless claim rests on Watts's own digital-domain tests and listening; the archive contains no independent measurements.
• Settings advice is his own preference or example, not a prescription for particular headphones.
• The 4.4 mm settings statement and the 2025-2026 remarks come from interviews.
• Quartet's EQ is described as more complex; nothing here about Mojo 2's controls carries to it.

Topics: EQ, tone controls and room correction