Spectro vs Spek: Which Is Better for Detecting Fake Lossless Audio on Mac?

Spek has been the go-to spectrum analyzer for DJs and audiophiles for years. It's free, it's simple, and it gives you a visual of your audio file's frequency content. But if you're trying to detect fake lossless files in your DJ library, Spek has a fundamental limitation: it shows you the data, but it doesn't interpret it for you.

Spectro was built to close that gap.

What Spek does

Spek renders a spectrogram — a color-coded image of the frequency content of your audio file over time. A trained eye can spot a fake lossless file by looking for a hard horizontal cutoff in the 16-20 kHz range, which is the fingerprint of MP3 encoding.

The problem is that "trained eye" part. Reading spectrograms accurately takes practice, and even experienced users disagree on borderline cases — especially in the 19-20 kHz range where 256 kbps MP3s and high-quality VBR files look nearly identical.

Spek also hasn't been updated in years. It runs on Apple Silicon Macs only through Rosetta 2 emulation, and it processes one file at a time.

What Spectro does differently

Spectro runs the same spectral analysis under the hood, but adds an interpretation layer on top. Instead of showing you a spectrogram and leaving the decision to you, it returns an automatic verdict:

• LOSSLESS — frequency content extends to 20 kHz or above, consistent with a genuine lossless source
• FAKE — hard cutoff detected below 20 kHz, consistent with a transcoded MP3 or AAC source
• MEDIUM — ambiguous range, typically 256 kbps or high-quality VBR

Every verdict comes with a confidence score and a diagnostic panel that explains the reasoning in plain language — no spectrogram reading required.

Feature comparison

	Spek	Spectro
Automatic verdict	✗	✓
Batch processing	✗	✓
Native Apple Silicon	✗ (Rosetta 2)	✓
Confidence score	✗	✓
Finder Tags integration	✗	✓
Clip detection	✗	✓
Spectrogram view	✓	✓
Free	✓	Trial (100 files)
Price	Free	$39 one-time

When Spek still makes sense

Spek is still useful if you want to visually inspect a specific file and you know how to read a spectrogram. It's also the right tool if you're analyzing audio for reasons beyond fake lossless detection — room acoustics, mastering checks, or any scenario where you want to explore the full frequency picture without automation getting in the way.

When Spectro makes more sense

If your goal is to audit a DJ library for fake lossless files, Spectro is the faster path. Drag in a folder of 200 tracks, wait a few minutes, filter by FAKE — done. No spectrogram interpretation, no file-by-file manual review.

Spectro's detection method is backed by peer-reviewed research: D'Alessandro & Shi (MP3 Bit Rate Quality Detection through Frequency Spectrum Analysis, ACM MM&Sec 2009) achieved 99% accuracy detecting transcoded audio across 2,512 songs. The only known ambiguous case — 256 kbps CBR versus VBR-0 — is flagged explicitly as MEDIUM rather than forced into a wrong verdict.

The verdict

For manual inspection of individual files: Spek works fine. For bulk library audits on a modern Mac: Spectro is the better tool.

If you want to go deeper on the detection method, How to Detect Fake Lossless Audio Files on Mac covers the full process — manual and automatic.