No it's not, yours is. You'll find hundreds of references on the Internet that describe this standard, and hundreds of pro level devices with a -10dB switch with the manual that describes its purpose is to support consumer grade line level connections.
And I know preamp nowadays output 2V, I didn deny that. But that doesn't automatically makes it a standard for all types of analog connetions and it doesn't mean designers are forced to implement it. If that would be the case than please first start a legal case against Naim for using DIN connectors.
Hmmm. Just few to mention:
Denon DCD-2560 CD player
Sidebar 1: Specifications
Description: 20-bit 16x-oversampling CD player. Frequency range: 2Hz–20kHz. S/N ratio: 116dB. Separation: 110dB at 1kHz.
Output level: 2V RMS.
Dimensions: 17 3/32" (434mm) W by 4 51/64" (104mm) H by 14 1/64" (360mm) D. Weight: 23lb (10.5kg).
Price: $750
(1992); no longer available (2020). Approximate number of dealers: 450.
Sony CDP-X779ES CD player
Sidebar 3: Specifications
Description: One-piece CD player. Front-panel controls: Digital Output select, track step, forward/reverse shuttle, Drawer open/close, Play, Pause, Stop, Line Out/Phone Level, Play Mode, Display Mode, AC Power. Remote controls: All the above, plus Peak Search, File Recall, Continue, Shuffle, Program, Custom Index, number buttons (0 to 20), program Clear, custom File, Erase file, Fader, Slow/fast search, Index search, A–B Repeat, Time, over-20 numeric, Check.
Outputs: fixed and variable single-ended line and fixed balanced line, 2V at 50k ohms, headphones up to 100mW into 32 ohms, coaxial digital 0.5V p–p at 75 ohms, optical digital. Frequency response: 2Hz–20kHz ±0.3dB. S/N ratio: >119dB. Dynamic range: >100dB. Harmonic distortion: <0.0015%. Channel separation: >100dB. Power consumption: 38W.
Naim CD5 XS CD player
Sidebar 1: Specifications
Description: CD player. Analog outputs: 5-pin DIN, 1 pair RCA. Digital outputs: 1 BNC. Frequency response: 10Hz–20kHz, +0.1/–0.5dB. Maximum
output level: 2.1V RMS at 1kHz (fixed). Output impedance: 10 ohms maximum. THD+N: <0.1%, 10Hz–18kHz at full level.
Re CD players, it would be possible to list hundreds of them with 2V output voltage.
Now for preamps, even much higher output level is available
Pass Laboratories XP-32 line preamplifier
Sidebar 1: Specifications
Description: Solid-state, three-chassis stereo preamplifier with remote control. Inputs: 5 single-ended (RCA) or balanced (XLR), 1 single-ended (RCA) or balanced (XLR) tape, 1 single-ended (RCA) or balanced (XLR) Pass Thru. Outputs: 3 single-ended line-level (RCA) or line-level balanced (XLR), 1 tape (RCA). Maximum gain: 9.6dB, balanced. Input impedance: 42k ohms, balanced; 22k ohms, single-ended. Output impedance: 50 ohms, balanced; 25 ohms, single-ended.
Maximum output: 23V RMS at 0.1% THD.
MBL Noble Line N11 line preamplifier
Sidebar 2: Specifications
Description: Solid-state, stereo line preamplifier with "MBL Unity Gain," remote control, and MBL SmartLink connectivity. Inputs: 5 pairs single-ended (RCA), 2 pairs balanced (XLR), and option for either phono MC (RCA) or 3rd pair balanced (XLR). Outputs: 5 pairs variable outputs in two groups—(Group 1) 2 single-ended (RCA) + 1 balanced (XLR), (Group 2) 1 single-ended (RCA) + 1 balanced (XLR)—and 2 pairs fixed outputs, 1 single-ended (RCA) and 1 balanced (XLR). Input impedance: 2.3k ohms (CD-In), 10k ohms (XLR-In), 50k ohms (Aux-In), 100 ohms (optional MC-In/internally adjustable). Output impedance: 100 ohms (RCA), 200 ohms (XLR). Voltage gain: For RCA and XLR out, 0dB in Unity Gain, 8dB in Regular Gain. Frequency range: DC–200 kHz (RCA and XLR) for all line-level inputs and outputs. S/N (A-weighted): 123dB (RCA), 117dB (XLR) in Unity Gain mode. THD+N: <0.001% for all line in and out in Unity Gain Mode.
Maximum output: 8V RMS (XLR and RCA).
Benchmark LA4 line preamplifier
Sidebar 2: Specifications
Description: Solid-state, stereo line preamplifier with touch-screen and remote control. Inputs: 2 pairs single-ended (RCA), 2 pairs balanced (XLR). Outputs: 1 pair stereo single-ended (RCA), 1 pair stereo balanced (XLR), 1 mono balanced (XLR). Input impedance: >50k ohms (balanced/unbalanced). Output impedance: 60 ohms (balanced); 30 ohms (unbalanced). Frequency response: –0.005dB at 10Hz, –0.001dB at 20kHz (balanced); –0.008dB at 10Hz, –0.005dB at 20kHz (unbalanced). S/N (A-weighted): 137dB (balanced), 116dB (unbalanced). Output noise (20Hz–20kHz): <2.1µV (balanced), <8µV (unbalanced). THD+N (20kHz bandwidth): –115dB (balanced).
Maximum output: 19.5V RMS (balanced), 3.2V RMS (unbalanced).
Source: reviews at www.stereophile.com