Where our knowledge comes from.
And where it doesn't.

The originator of the thing itself. If you write about a controller, you cite the manufacturer. If you write about GEMA, you cite GEMA.

Typical examples: Manufacturer manuals, legislation, GEMA tariffs, audio standards, platform terms

• DDJ-FLX2 — Bedienungsanleitung (User manuals & documentation)
  AlphaTheta Corporation·Manufacturer·2024-11-14·retrieved 03.08.2026

  German edition, 156 pages. The dates contradict each other: 14.11.2024 on the documentation page, 29.10.2024 in the German support article. To be resolved at the next re-check.

• Company information — AlphaTheta Corporation
  AlphaTheta Corporation·Manufacturer·2020-01-01·retrieved 04.08.2026

  Evidence for: the renaming of Pioneer DJ Corporation to AlphaTheta Corporation as of 01.01.2020; the Pioneer DJ brand remained in place; new products now also appear under the AlphaTheta brand.

• DDJ-FLX2 — Produktseite (Features & Spezifikationen)
  AlphaTheta Corporation·Manufacturer·retrieved 03.08.2026

  Evidence for the mixer's controls: EQ knobs, channel faders, crossfader — NO gain/trim knob, no dedicated loop in/out buttons (loops run via the performance pads).

• CDJ-3000 — Bedienungsanleitung (User manuals & documentation)
  AlphaTheta Corporation·Manufacturer·2020-09-15·retrieved 03.08.2026

  German edition, document date 15.09.2020.

• Tarif VR-Ö — Vervielfältigung zum Zwecke der öffentlichen Wiedergabe
  GEMA·Institution·2026-01-01·retrieved 04.08.2026

  Edition valid from 01.01.2026. The licence applies per reproduced work and has no time limit; +20 % surcharge for GVL neighbouring rights. The actual amounts appear only in the tariff document, not on the page.

• § 15 UrhG — Allgemeines (Gesetz über Urheberrecht und verwandte Schutzrechte)
  Bundesministerium der Justiz / Bundesamt für Justiz·Law·2024-10-23·retrieved 03.08.2026

  Consolidated status: last amended by Art. 28 G of 23.10.2024. Para. 2: the right of communication to the public; para. 3: when a communication counts as public.

• rekordbox Instruction Manual
  AlphaTheta Corporation·Manufacturer·2026-07-06·retrieved 04.08.2026

  Version 7.2.16, 265 pages, in English — full text in the archive. Menu paths and feature set can change with every update. ⚠️ A complete GERMAN edition of the 7.x manual does not exist — in German there is only a 30-page introduction to 7.2.14. Waiting for it was waiting for something that isn't there. Current software on 10.08.2026: 7.2.17 (30.07.2026).

• Camelot Wheel
  Mixed In Key LLC·Manufacturer·retrieved 03.08.2026

  Primary source: the Camelot system comes from Mixed In Key.

• What is the audio quality like with Beatport Streaming?
  Beatport·Platform·2026-05-05·retrieved 03.08.2026

  Streaming quality only. Evidence for neither download formats nor track prices.

• Der GEMA DJ-Tarif
  GEMA·Institution·retrieved 03.08.2026

  Tariff VR-Ö concerns the DJ's reproduction rights, separate from the organiser's performance right.

• R 128 — Loudness normalisation and permitted maximum level of audio signals
  European Broadcasting Union·Standard·2023-11·retrieved 03.08.2026

  Version 5.0. Target value −23 LUFS for broadcast. Does not cover streaming targets.

• Häufig gestellte Fragen — Über rekordbox 7 (Hardware Unlock)
  AlphaTheta Corporation·Manufacturer·2026-01·retrieved 10.08.2026

  As of January 2026. Evidence for the hardware unlock of the DDJ-FLX2, not for the full feature set of the paid plans.

• DJM-A9 — All specifications & features
  AlphaTheta Corporation·Manufacturer·retrieved 10.08.2026

  Evidence for the 3-band EQ and the additional isolator mode of the DJM range.

• Introducing DDJ-FLX2 — kompakter 2-Kanal-DJ-Controller
  AlphaTheta Corporation·Manufacturer·2024-10-29·retrieved 10.08.2026

  Evidence for the class compliance of the DDJ-FLX2. At the same time refutes an optional Pioneer ASIO driver for this model. Taken from the research report of 2026-08-10 (docs/quellen-archiv/recherche/).

• DJM-900NXS2 — Produktseite (4-Kanal-DJ-Mixer)
  AlphaTheta Corporation·Manufacturer·retrieved 10.08.2026

  Evidence for 4 channels and the independent send/return. NOT evidenced: the booth level control and the EQ range of this model. Taken from the research report of 2026-08-10.

• TRAKTOR KONTROL D2 — Benutzerhandbuch
  Native Instruments·Manufacturer·retrieved 19.08.2026
• Serato DJ Pro — User Manual
  Serato·Manufacturer·retrieved 19.08.2026
• Audio Encoding 101
  Serato Limited·Manufacturer·retrieved 10.08.2026

  Manufacturer recommendation of 320 kbps CBR joint stereo for lossy DJ files. Not a standard, not a minimum requirement. Taken from the research report of 2026-08-10.

• Why is Beatport increasing prices?
  Beatport·Platform·2026-05-05·retrieved 10.08.2026

  Evidence for the single-track prices in euros (1,59 / 1,39 / 2,39 € plus a 0,75 € lossless surcharge) and the lossless formats WAV/AIFF. Independently confirmed by Beatport's own price table in the archive.

• Safe listening devices and systems: a WHO-ITU standard
  World Health Organization / International Telecommunication Union·Institution·2019·retrieved 10.08.2026

  Evidence for: hearing damage from loud sound is irreversible, the recommended limit for recreational noise (below 80 dB, max. 40 h/week) and the dose logic behind it. Full text in the archive.

• DGUV Information 209-023 — Lärm am Arbeitsplatz
  Deutsche Gesetzliche Unfallversicherung e.V. (DGUV)·Institution·2021-11·retrieved 10.08.2026

  Evidence for the German action values of 80/85 dB(A) and the threshold below which there is no risk of irreversible hearing damage. Full text in the archive.

• Recommendation ITU-R BS.1770-5 — Algorithms to measure audio programme loudness and true-peak audio level
  International Telecommunication Union·Standard·2023-11·retrieved 10.08.2026

  The measurement specification behind LUFS and true peak. Version -5 of 11/2023. Full text in the archive.

• Loudness normalization on Spotify
  Spotify·Platform·retrieved 10.08.2026

  Evidence for the target value -14 LUFS and the reference to ITU 1770. Explicitly does NOT apply to the web player and third-party devices.

• Wird SoundCloud meinen Track auf dem Level abspielen, auf dem er gemastert wurde?
  SoundCloud·Platform·retrieved 10.08.2026

  Evidence for -14 LUFS integrated at max. -1 dBTP as the master recommendation. The minus signs were lost in the extracted text — check against the original.

• DDJ-200 — Bedienungsanleitung
  AlphaTheta Corporation·Manufacturer·retrieved 11.08.2026

  German edition, 193 pages. In the buying guide under “Best choice to start with”.

• DDJ-FLX4 — Bedienungsanleitung
  AlphaTheta Corporation·Manufacturer·retrieved 11.08.2026

  German edition, 177 pages.

• DDJ-REV1 — Bedienungsanleitung
  AlphaTheta Corporation·Manufacturer·retrieved 11.08.2026

  German edition, 66 pages. A Serato device — no rekordbox support.

• DDJ-FLX6 — Instruction Manual
  AlphaTheta Corporation·Manufacturer·retrieved 11.08.2026

  English edition, 122 pages. ⚠️ Documents the DDJ-FLX6, NOT the FLX6-GT from our buying guide. Carries only statements that hold for both; anything GT-specific needs the GT manual.

• DDJ-400 — Service Manual (ORDER NO. QRT1023)
  Pioneer DJ Corporation·Manufacturer·2018·retrieved 11.08.2026

  English, 82 pages, merged from two partial PDFs. ⚠️ A service manual for technicians, NOT the operating instructions — it carries hardware specifications (from p. 5) but nothing about operation.

• Hercules DJControl Inpulse 200 — Benutzerhandbuch
  Guillemot Corporation (Hercules)·Manufacturer·retrieved 11.08.2026

  German edition, 24 pages, DJUCED software. ⚠️ Documents the Inpulse 200, NOT the MK2 recommended in our buying guide. Unusable for MK2-specific statements.

• Plans & pricing — rekordbox
  AlphaTheta·Manufacturer·retrieved 12.08.2026

  Four tiers: Free, Core, Creative, Professional. Taken 2026-08-12 from the manufacturer's page; amounts in euros per month.

• Serato DJ Pro — Pricing
  Serato·Manufacturer·retrieved 12.08.2026

  A perpetual licence and a monthly subscription, quoted in US dollars. Taken 2026-08-12; the monthly subscription was last raised in October 2025.

• Traktor Pro 4 — Presseinformation
  Native Instruments·Manufacturer·retrieved 12.08.2026

  Traktor Pro 4 separates any track into four stems (drums, bass, vocals, remaining instruments) without preparing the file.

• Spotify & DJ Software
  Spotify·Platform·2025-09-24·retrieved 12.08.2026

  Integration into rekordbox, Serato and djay, available since 2025-09-24 for Premium accounts, Germany included. Evidence for availability, not for the scope of the licence.

• DDJ-FLX2 — Einsteiger-Controller mit eingebautem Audio-Interface
  AlphaTheta·Manufacturer·retrieved 12.08.2026

  The DDJ-FLX2 replaces the DDJ-200 and, unlike it, brings a built-in audio interface. Taken 2026-08-12.

• Gebühren für die Anmeldung einer deutschen Marke
  Deutsches Patent- und Markenamt·Institution·retrieved 12.08.2026

  290 € basic fee for an electronic application covering up to three Nice classes, each further class 100 €. Taken 2026-08-12.

• Mixed In Key — Preise
  Mixed In Key·Manufacturer·retrieved 12.08.2026

  Standard licence 58 US dollars one-off, alongside Pro and Suite. Taken 2026-08-12.

Established literature and public bodies. Always secondary literature — it reports on something, which is why it is never tier A.

Typical examples: Specialist books with an ISBN, academic papers with a DOI, chambers of commerce, consumer advice centres

• Dance Music Manual
  Focal Press·Specialist book·2024-09-12·retrieved 03.08.2026

  5th edition (2024). ⚠️ The research report of 2026-08-10 consulted the 4th edition (2019) — the page numbers in the code comments refer to that one and do NOT apply to this edition. Evidence taken from it: the BPM definition (ch. 16), genre tempos for house/techno/drum & bass/trance (ch. 27-32), level summation in the bass (ch. 17) and explicitly that there are NO universal LOW/MID/HIGH boundaries (ch. 34). The link points at a book wholesaler and should move to the publisher's page.

• The Mixing Engineer's Handbook
  Bobby Owsinski Media Group·Specialist book·2025-10-06·retrieved 03.08.2026

  6th edition.

• How To DJ (Properly)
  Bantam Press·Specialist book·2006-11-20·retrieved 03.08.2026
• Unlocking the Groove: Rhythm, Meter, and Musical Design in Electronic Dance Music
  Indiana University Press·Specialist book·2006-11-15·retrieved 10.08.2026

  Evidence for the definition of four-on-the-floor (p. 78), NOT for its historical origin. Taken from the research report of 2026-08-10.

• Preisvergleich DJ-Controller (Deutschland)
  Geizhals·Trade publication·retrieved 12.08.2026

  German retail prices, taken 2026-08-12: DDJ-FLX4 from about 295 €, DDJ-REV1 from about 256 €, DDJ-FLX2 from about 156 €. Street prices, not manufacturer figures — which is why the text says “about” throughout.

Editorially run industry media with an imprint. Enough for market and practice statements — never for law, health or hard technical figures.

Typical examples: Trade magazines and portals of the DJ and audio industry

• Loudness Targets For Streaming Platforms
  Mastering The Mix·Trade publication·retrieved 10.08.2026

  Trade publication with an imprint. Evidence for loudness targets on platforms that publish NO figures of their own (YouTube, club play). Contradicts the primary source on SoundCloud — there SoundCloud itself applies.