M2DX vs K.O. II
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
M2DX
Create music with a powerful 6-operator FM synthesizer. Explore hand-crafted presets or import classic DX7 banks. Use the on-screen keyboard or connect MIDI controllers for a versatile music-making experience.
- 6-operator, 32-algorithm FM synthesis
- On-screen keyboard with velocity control
- DX7-format .syx bank import
- 6-stage FX chain
- AUv3 plug-in support
- Native MIDI 2.0 support
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M2DX is a 6-operator, 32-algorithm FM synthesizer for iPhone, built from the ground up in pure Swift 6. Open it and play immediately — tap the built-in on-screen keyboard and start making sound with M2DX's own hand-crafted presets. No external hardware or MIDI controller is required. The FM engine is a bit-exact port of the open-source Dexed / msfa DSP, verified sample-for-sample against the reference. It is also compatible with the classic DX7 patch format: bring your own DX7-format .syx banks and play them alongside M2DX's originals. KEY FEATURES - Built-in on-screen keyboard with velocity and octave control — play standalone, no hardware needed - 6-operator, 32-algorithm DX7-style FM synthesis - M2DX's own original FM presets, plus DX7-format .syx bank import (bring your own) - A 6-stage FX chain: EQ, Drive, Chorus, Reverb, Stereo, Maximizer - Low-latency audio with AVAudioSourceNode direct rendering - AUv3 plug-in — use M2DX as an Audio Unit (AUv3) in compatible hosts OPTIONAL MIDI (not required to use the app) - Connect any MIDI controller over Bluetooth or USB if you have one - Native MIDI 2.0 — UMP with 16-bit velocity and 32-bit controllers - MIDI-CI Property Exchange — patch names appear on compatible controllers (for example, KORG KeyStage) - MIDI Learn for hands-on control MIDI 2.0 done natively, classic FM done faithfully. The FM engine is built on Dexed / msfa (Apache License 2.0). M2DX is an independent product and is not affiliated with, endorsed by, or sponsored by Yamaha Corporation. DX7 and Yamaha are trademarks of Yamaha Corporation. iOS 18 or later.
K.O. II
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K.O. II is a compact native beat-making instrument for iPhone and iPad. Tap responsive pads, switch between drum, percussion, bass, and key banks, build 16-step patterns, and explore 38 included demo grooves. Designed as a focused standalone music surface, K.O. II gives you a hardware-inspired workflow for quick ideas, rhythm practice, and portable sound experiments.
Screenshots
Verdict
The clearest difference is in-app purchases: K.O. II at none against M2DX's 1. K.O. II also leads on iOS requirement (16.0 vs 18.0). On price, ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. M2DX sells 1 one-off in-app purchase. K.O. II asks for nothing beyond the download.
| Parameter | M2DX | K.O. II |
|---|---|---|
| Price | Free | Free |
| Rating | 3.7 (3 ratings) — better | — |
| Positive reviews | 25.0% of reviews | — |
| Number of ratings | 3 — better | — |
| Update frequency | Every 2 days | — |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free | — |
| Devices | iPhone | iPhone, iPad — better |
| Requires iOS | 18.0 | 16.0 — better |
| Further details — not scored | ||
| Size | 16 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | Hakaru Hirose | 海洋 符 |
In-app purchases
M2DX
- M2DX Pro Unlock$9.99
K.O. II
No in-app purchases








