You have a loop you love and no idea what key it is. Or you have a keyboard under your hands and a fear of playing a wrong note. Tonic 2 and Guardrail both promise in-key chords, but they start from opposite ends of that problem.
This comparison draws only on MusicTech's weekly plugin roundup (https://musictech.com/news/gear/new-plugins-this-week/). The roundup is a news summary, not a review, so every claim below is a documented description unless marked as an inference or a gap. The roundup publishes no latency figures, accuracy measurements or hands-on results, so this comparison has none.
What you are actually comparing
The roundup describes Zplane's Tonic 2 as a major update to the company's existing key and scale detection plugin. Detection is the foundation, and the chord features sit on top.
It describes Denormal's Guardrail as a "creative MIDI transformer". The roundup frames it around performance: you play, and it keeps you in key. It does not mention key detection from audio.
That difference is the whole decision. One starts with analysis, the other with your hands.
Starting from audio versus starting from a keyboard
If you begin with a sample, a loop or a recorded part, Tonic 2 is the documented fit. The roundup says the new version adds a keyboard section with extra options for playing chords within the detected key. It is an inference, not a documented detail, that the chord options follow the detected key. The roundup does not explain how detection works or how it handles key changes.
If you begin with a controller and an empty project, Guardrail is the documented fit. You play in-key chords on the white notes and add passing tones and extensions on the black notes. The roundup does not say how Guardrail knows which key you want, whether you set it manually, or whether it can follow anything in your session. Check the product page before buying.
Tonic 2 also accepts MIDI input in this version, so you can play it from a controller too. The roundup does not document how its playing options compare with Guardrail's.
MIDI in, MIDI out and getting chords onto the timeline
Both plugins document a route from performance to the DAW timeline, but the routes differ.
According to the roundup, Tonic 2 accepts MIDI input and can route MIDI out to play external instruments. You can also drag chords out of the plugin into the DAW timeline as MIDI clips. Of the two, that is the more complete documented MIDI path. For more on this, see more on is plugin boutique gold tier worth it? spend math guide.
Guardrail captures your input into a Performance List as soon as you press play. You can drag that straight into the DAW timeline for arranging and editing. The roundup says this eases the process of recording MIDI, but it does not state what format the dragged material takes. MIDI is the natural reading.
The roundup does not say whether Guardrail sends MIDI out to hardware or other plugins. It also says nothing about DAW-specific drag-and-drop behaviour. DAW compatibility is a real risk with drag features, so put it on your trial checklist.
Performance controls
Here Guardrail documents far more. The roundup lists:
- White notes for in-key chords, and black notes for passing tones and extensions.
- Exact or Compact modes for spacing the notes within a chord.
- Octave changes and randomisation.
- Strumming chords with the pitch wheel.
- Arpeggiating chord notes with the mod wheel.
If you play live and want hands-on control, that list is concrete. Your controller likely needs a pitch wheel and a mod wheel, or another way to send those messages, to use the strum and arpeggio tools. That is an inference from the description, so confirm the mapping in the manual.
The roundup's Tonic 2 entry mentions "extra options for playing chords within the detected key" without naming them. It does not document strum, arpeggio, voicing modes or randomisation for Tonic 2. That is a gap in the roundup, not proof the features are absent. Check the Zplane product page. We cover related ground in jupiter-08 vs n/vision: which roland boutique to buy? in depth.
Price, launch offers and trial terms
Guardrail has a launch price of €39 and a full price of €59. The roundup gives no end date for the launch price.
The roundup gives no Tonic 2 price, so this article states none. Don't assume it is cheap, and don't assume what existing owners will pay. The roundup does not document upgrade pricing either.
On trials, the roundup says only that most developers offer free trials for their plugins in general. It does not confirm a trial for either plugin. Verify trial availability, length and restrictions on each vendor's page.
Side-by-side summary
| Feature | Tonic 2 (Zplane) | Guardrail (Denormal) | | --- | --- | --- | | Core purpose | Documented: key and scale detection with chord-playing options | Documented: creative MIDI transformer for in-key chord performance | | Key detection from audio | Documented as the plugin's base function; method not described | Not documented | | MIDI input | Documented | Implied by the play-and-capture design; not stated explicitly | | MIDI output | Documented: routes out to external instruments | Not yet verified | | Chords to DAW timeline | Documented: drag out as MIDI clips | Documented: drag from the Performance List | | White/black-note mapping | Not yet verified | Documented | | Strum / arpeggio | Not yet verified | Documented: pitch wheel strum, mod wheel arpeggio | | Voicing / spacing | Not yet verified | Documented: Exact or Compact | | Randomisation | Not yet verified | Documented | | Interface | Documented: streamlined, modernised, resizable | Not documented | | Price | Not yet verified | Documented: €39 launch, €59 full | | Plugin formats, system requirements | Not yet verified | Not yet verified |
Which one fits your workflow: a checklist
Investigate Tonic 2 if:
- You have a sample or loop and need its key before you write over it.
- You want chords dragged out as MIDI clips, with the option to send MIDI to an external instrument.
- You can confirm its price before committing.
Also read: minifreak 49 vs minifreak: is the €799 upgrade worth it?
Investigate Guardrail if:
- You want to play chords on your keys and stay in key without theory knowledge.
- You like the idea of strumming with the pitch wheel or arpeggiating with the mod wheel.
- You want a documented €39 launch price and a capture list of what you just played.
Choose neither if you already know your keys and your DAW has a chord track or scale-lock tool you like. Nothing in the roundup suggests either plugin does something impossible elsewhere. It documents convenience.
What to test before you pay
Run these in your own DAW during a trial, and confirm a trial exists first.
- Load the plugin as a MIDI effect and check that your DAW routes its MIDI output to a synth. Hosting rules for MIDI effects vary by DAW.
- Drag a chord out to the timeline. Check that it lands as editable MIDI notes, at the right tempo and position.
- For Tonic 2, feed it a loop with a known key and a loop you suspect is ambiguous. Compare each result with what you hear, and record your own findings, since the roundup documents none.
- For Guardrail, play with your actual controller and confirm the pitch wheel and mod wheel do what the roundup describes.
- Save and reopen a project to check that the plugin recalls its settings and captured performances.
- Check the price, upgrade terms and plugin format on the vendor page.
The verdict, from documented material only: pick Tonic 2 if your songs start from existing audio and you need the key first. Pick Guardrail if your songs start on your keyboard and you want performance tools at a documented €39 launch price. If you want both jobs in one plugin, trial both, because the roundup does not show that either does the other's job.
