Stratus vs Positive Grid Spark 2: AI Pedal vs AI Practice Amp

Last updated: August 31, 2026. Spark 2 specs below come from Positive Grid's product page and official spec sheet; all sources are listed at the end.

This one's a little different from our usual comparisons, and we want to be upfront about it: the Positive Grid Spark 2 is not a pedal. It's a 50-watt smart practice amp with speakers built in, and it's one of the best-loved products in guitar right now. But if you search "AI guitar tone," Spark 2 and Stratus show up in the same results — both promise that you can describe a sound and get it back — so plenty of players are genuinely choosing between them. Here's how the two AI philosophies (and the two very different boxes they live in) actually compare.

The short version

• Spark 2 is a complete practice room in one box. Speakers, Smart Jam backing tracks, Auto Chords, a looper with hundreds of drum grooves, Bluetooth streaming, and a 100,000-tone community. For playing at home, it's brilliantly built for the job — a job Stratus leaves to your amp, because a pedal's job is to travel.
• The AI does different work in each. Spark AI listens to your description and serves up matching tone options from Positive Grid's library of 33 amps and 43 effects. The Stratus AI FX Builder writes brand-new effect DSP from scratch. One finds your sound; the other invents sounds that didn't exist.
• Stratus is the one that goes on a pedalboard. 11.6 oz vs 12.1 lb, real amp captures through Neural Amp Modeler, hands-free presets, and MIDI. Spark 2 stays home most nights — by design, and happily.

Side by side

How the AI actually works

Three products now ship "describe your tone" AI, and they all mean something different by it. Here's the honest breakdown of these two.

Spark AI (Beta): inside the Spark app, you name an artist, a song, or just a feeling, and Spark AI answers with multiple tone options assembled from Positive Grid's gear library — audition them, keep what you like, ask for more. Positive Grid says it gets smarter the more you use it, and it's free. As a way to skip menu-diving and land on a good sound fast, it's genuinely slick, and it draws on one of the deepest model libraries in the practice-amp world.

Stratus AI FX Builder: describe an effect — not a preset, an effect — and the builder writes new FAUST DSP code for it, runs it through multiple rounds of compilation checks, automated code review, and audio-output testing (about 95% of builds deliver a working effect), and sends it to your pedal wirelessly. Advanced Mode shows you the code. Every account gets 30 free builds a month, with paid plans for heavy users.

The difference in scope: Spark AI finds your tone within Positive Grid's catalog — 33 amps and 43 effects, all excellent, all finite. The FX Builder's output isn't drawn from a catalog at all; if you can describe an effect nobody has made, it can still write it. The difference in polish: everything Spark AI hands you is built from Positive Grid's hand-tuned models, so there's no failure case to speak of. Two valid philosophies — discovery versus invention.

Amp tones

Spark 2's amps are Positive Grid's own HD models — all 33 remastered for the new DSP engine, covering electric, acoustic, and bass — plus a ToneCloud community with over 100,000 shared tones. That library, refined across millions of Spark players, is a real strength.

Stratus goes the capture route: it runs Neural Amp Modeler Architecture 2 natively, so your amp tones are captures of actual amps — 500,000+ free captures and IRs on TONE3000, browsable from the app, or capture your own rig for free. When TONE3000 launched A2 they published their testing: quantitative comparisons across 39 tones and a blind listening study with over 1,000 participants, where A2 came out ahead of several major capture formats (test code and data are open source). Spark's models weren't part of that study, so we won't claim a head-to-head result that doesn't exist — the point is simply that Stratus's amp section is built on an open format with published evidence behind it, and it sounds like the specific amps people captured.

At home

Let's give Spark 2 its full due here, because this is what it was born for. It is the practice room: 50 watts of stereo FRFR sound, Smart Jam building backing tracks around your playing, Auto Chords showing you the changes to any song in real time, two loopers with hundreds of drum grooves, Bluetooth for jamming along to anything, and a headphone jack for midnight sessions. No practice amp does the "pick me up and lose an hour" thing better.

Stratus doesn't try to be the room — it's the rig. It makes no sound on its own and has no headphone jack, so home playing means your amp, an FRFR, or an interface. What you get for that trade is that the sounds you build at home are exactly what you take to rehearsal and the gig, on the same 11.6-ounce pedal, with a five-minute looper and tuner along for the ride.

On the board and on stage

This is Stratus territory the way the living room is Spark's. It's a pedal: it sits on a board, runs on standard 9V pedal power (or USB-C), gives you 14 presets hands-free through its color-coded footswitch pairs, stores 128 total, and takes full MIDI control — program changes, per-effect bypass, looper transport — over USB. We've built custom Stratus algorithms for players like ZZ Top's Billy Gibbons, and the whole point is that the pedal disappears into any rig.

Spark 2 can leave the house more than you'd think — stereo line outs, an optional battery for 12 hours of cordless playing, and the optional Spark Control X footswitch for hands-free switching — and for a busking session or a small jam it's a self-contained PA. It's just carrying a different job description: the speaker is the product, and 12 pounds is the price of the speaker.

Cost of ownership

Spark 2 is $349 with everything included; the battery ($79) and Control X footswitch ($159) are the optional extras most owners eventually eye. Stratus is $299 with 19 effects free, premium effects from $14.90 (or the 22-effect bundle at $99), half a million free captures and IRs, free community effects on Chaos Cloud, and 30 free AI builds a month with paid tiers above. Fully loaded, either lands in the same neighborhood — the money just buys speakers and jam tools on one side, and effects, captures, and a generative AI on the other.

Openness

Positive Grid's ecosystem is deep but closed: the models are theirs, and the community lives inside ToneCloud — which, to be fair, is a thriving place with 100,000+ tones. Stratus is built on open pieces: NAM as the capture format, FAUST source access for every effect the AI writes, free VST/AU plugin versions, and a Tone Shop where third-party developers keep 75% of sales. If you'll never look under the hood, both serve you fine; if you might, only one has a hood that opens.

Which should you buy?

Buy the Spark 2 if: you mostly play at home, you want one box that makes sound the second you plug in, and features like Smart Jam, Auto Chords, and a drum-backed looper would genuinely get you playing more. It's the best-in-class version of what it is, and $349 is honest money for it.

Buy the Stratus if: you have (or plan to have) an amp, an FRFR, or an interface, and what you want is the rig itself — real amp captures, a chain you design, an AI that invents effects instead of finding them, and a box that goes wherever the gig is. That's the pedal we built, and at $299 it costs less than the amp that stays home.

And honestly? Plenty of players end up with both jobs covered — a speaker for the room and a rig for the world. Just know which job you're hiring for.

Sources

• Positive Grid — Spark 2 product page (price, features, Spark AI, specs, dimensions)
• Positive Grid — Spark 2 technical specifications (looper length, USB interface, power)
• TONE3000 — NAM Architecture 2 (A2) (test methodology and results; code and data are open source)
• Chaos Audio — Stratus product page (Stratus specs and pricing)

Want the rig that leaves the house? The Stratus is $299 with free US shipping — and your first 30 AI builds are on us every month.