S2pd

Desktop App for macOS · Version 1.1

Smrt Stem

Your pre-flight check for stem deliveries. Drag in a folder, get a clear verdict, move on with your life.

Buy Now · $59 Try Free

Full app, 14 days, no credit card.

Smrt Stem 1.1 checking a delivery cue by cue, with a mix loaded as the reference and Null playing only the difference — Every cue on its own. Null plays only what's different from the mix.

New in version 1.1

Bigger. Smarter. Still stupid simple.

The biggest update since launch. Free for everyone with a Smrt Stem license.

Cue by cue. Drop a whole episode or album. Every folder is checked as its own cue, so your 30 second edit never gets flagged against the full-length stems.
Null. Play the stems against the flipped mix and hear only what's different: the missing part, the wrong take, the level change.
Loudness and true peak for every file, in the app and in your reports.
New checks for flipped polarity and a mix that runs past its stems.
A fader on every stem, Pro Tools-style shortcuts, and a new look.

Everything in 1.1 →

What It Does

Cue by Cue

Drop a single cue or a whole episode. Every folder with audio is checked as its own cue, and the cue tree takes you straight to the one with the problem.

Full Stem Analysis

Sample rate, bit depth, channels, length and format, plus loudness (LUFS) and true peak for every file. Every stem, one scan, every problem surfaced.

Audio Detection

Spots silence, clipping, clicks, pops and flipped polarity. The stuff your ears miss at 2am when you just want to hit send.

Reference and Null

Your mix sits on the same timeline as the stems. Flip between them, or hit Null to hear only what's different. Confirm that what you're sending matches what you approved.

Playback Engine

A fader on every stem, solo, mute, loop and Pro Tools-style shortcuts. No need to open a DAW just to double-check a delivery.

Pass / Warn / Fail

A clear verdict for every cue. Green means ship it, yellow means take a look, red means stop and fix.

Reports You Can Send

CSV and PDF reports with every file's numbers and every issue, cue by cue. Attach one to the delivery email. Receipts.

Stays on Your Machine

No internet required after activation. No tracking. No cloud. Your audio never leaves your computer.

Actual app. Actual verdicts.

See the answer before you hit send.

Every scan ends with a verdict you can understand at a glance, plus the file-level evidence to fix what is wrong.

Smrt Stem 1.1 player with every stem on one timeline, a fader on each stem, and the reference mix loaded — Every stem on one timeline, with its own fader. Solo it, loop it, null it against the mix.

Smrt Stem Pass verdict with green status and multitrack waveforms — Pass. Ship it.

Smrt Stem Warn verdict identifying possible click and pop artifacts — Warn. Take a listen where it tells you.

Smrt Stem Fail verdict showing delivery issues that need to be fixed — Fail. Fix it before your client finds it.

What It Doesn't Do

We'd rather you know this before you buy than find out after. Smrt Stem is great at what it does, and honest about what it doesn't.

🔇

Does not support surround or Atmos

Smrt Stem does not handle surround or Dolby Atmos stems. It's built for standard stereo and mono deliveries. If your workflow is surround-heavy, this isn't the tool for that (yet).

🎯

Detection is good, not perfect

The click and glitch detection catches the vast majority of issues, but it can occasionally miss something subtle or flag a false positive on complex transient material. It's a safety net, not a replacement for your ears on a final listen.

🎛️

Built for stems, not full mixes

You can scan a full mix through it, and it will catch clipping, silence, and format issues just fine. But the detection algorithms are tuned for individual stems. Dense full mixes can produce noisier results.

🍎

No Windows version (yet)

Windows is in the works, but it's not here yet. If you're on a PC, hang tight or drop us a line so we know there's demand.

📁

No batch queue

Drop a whole episode and Smrt Stem checks every cue in it. What it doesn't have is a batch queue for running several projects back-to-back while you sleep. Drag, scan, review, repeat.

Smrt Stem file table showing format, loudness and true peak for every file, with one stem flagged

One cue. Every file, with its loudness and true peak. The odd one out has nowhere to hide.

How It Works

1

Drag in your stems

A folder, a whole episode, or a few loose files. It reads WAV, AIFF and FLAC, plus MP3, AAC, M4A and OGG (lossy files get flagged).

2

Hit scan

Smrt Stem analyzes every file for format issues, audio problems, and consistency across the stems in each cue.

3

Get your verdict

Pass, warn, or fail. If something's wrong, you'll know exactly what and where.

4

Ship it

Fix what needs fixing, confirm by ear against your mix, and send your stems with confidence.

System
Requirements

OS macOS 13 (Ventura) or later
Older Mac? On macOS 12 or earlier, download Smrt Stem 1.0.11
Chip Intel or Apple Silicon
RAM 4 GB minimum
Disk About 550 MB for the app
Internet Required once for license activation, then runs fully offline

Questions

Is there a free trial?

Yes. 14 days, fully functional, nothing held back. If it earns a spot in your workflow, buy it. If not, it quietly expires.

What do I get when I buy?

A license key that works on up to 2 machines. One purchase, yours forever. No subscriptions, no annual renewals, no upgrade fees.

Is version 1.1 a free update?

Yes. Every 1.x update is free with your license. Smrt Stem offers it the next time you open the app. Version 1.1 needs macOS 13 (Ventura) or later; on an older Mac, 1.0.11 keeps working.

Can I get a refund?

Absolutely. Email me, tell me what went wrong, and I'll send your money back. Simple as that.

Does it work on Windows?

Not yet. Mac only for now. Windows is in the works.

What if I need more than 2 machines?

Need more than 2 machines? Email hello@s2pdaudio.com and I'll sort out an extra license for you.

Does it phone home?

Once, when you activate your license key. After that, fully offline. Zero telemetry, zero analytics.

Who made this?

A working composer who got tired of sending bad stems at midnight. More about S2pd.

Stop Guessing. Start Scanning.

Your stems are either right or they're not. Know before your client does.

$59 USD · one-time purchase

Buy Now Try Free

Full app, 14 days, no credit card.