NDX2-252 & Headroom,Volume leveling in ROON & NDX2 Attenuation

Streaming Audio
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Please comment on my solution for my setup (Headroom + Volume Leveling)

(note: I also tested NDX2 attenuation later on in the conversation)

I’ve been experimenting for quite a while with digital attenuation in Roon to get the NAC 252 volume control into its best operating range, and wanted to share what I’ve learned and what finally worked for me. I’d love to hear your thoughts.

System: NDX2 → NAC 252 → SuperCap → 250DR → Monitor Audio PL200.
Vinyl: Rega P8 → ND9 → Stageline MM.
Listening room: small; about 3m speaker distance and 3.4m listening distance.

Why I started this experiment

When listening to vinyl (Rega P8), I noticed something interesting:

  • When the 252 volume was around 9 o’clock, the sound was wide open, centered, and stable.

  • But with digital sources (NDX2) in my small room, I normally had to set the 252 at around 7:45–8:00 for ~70 dB average listening.

Below “8 o’clock,” the 252 volume control can sit in its least linear part of the analog pot, where channel matching isn’t as good. So my goal was:

  • :check_mark: Move my typical listening position into the 9–10 o’clock range

    :check_mark: Avoid channel imbalance at very low volume

    :check_mark: Keep the system sounding natural and dynamic

Tests I tried

I experimented with different combinations of:

  • Headroom Management

  • Volume Leveling

  • DSD → PCM conversion

  • Fixed vs dynamic attenuation

And I measured actual listening SPL:

  • Average: ~70 dB

  • Peaks: ~85 dB

  • Quiet listening: ~60–65 dB

  • Room is small, so these levels feel right.

The solution that finally works best for me (settings in ROON)

1. Volume Leveling: Auto, Target –25 LUFS

This gives consistent loudness across albums
(especially useful with mixed playlists or different mastering styles).

2. Headroom: –15 dB

This prevents clipping, leaves space for volume leveling adjustments, and ensures DSD→PCM peaks don’t overshoot.

3. Typical total attenuation: –25 dB

This moves the NAC 252’s volume position upward very nicely:

  • Soft listening: around 8 o’clock

  • Normal listening (70 dB): around 9:30

  • Loud: about 10 o’clock

Everything stays in the most linear part of the volume pot, with perfect channel balance.

4. Sound quality?

Balanced, open, controlled, and consistent.
There’s no sense of digital harshness or compression — Roon’s 64‑bit DSP is transparent.

Why this seems to work (short version)

  • Roon merges all gain changes (headroom + leveling) into one single DSP calculation.

  • The processing is 64‑bit floating point, so attenuation does not reduce resolution.

  • The 252 really performs best above 8 o’clock, so this approach helps reach that zone without changing hardware or cabling.

Open question to the forum

Has anyone else used a similar combination of Headroom + Volume Leveling to position the 252 or 282 volume pot in the optimal range?
Any long‑term observations or alternative approaches?

Note: i have done all my “research” using a self-made a HIFI AI agent in GPT and Co-pilot focussing on white papers, hifi magaziens and fora.

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Essentially the same as my config… different boxes, different numbers, but the same principle. I use ‘album’ rather than ‘auto’ though - makes more sense to me.

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Hi AndyR,
makes sense to do album, will change.

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I solved volume and balance issues with an attenuated cable between my XS3 and ND5XS2. The variable volume mode of the ND5XS2 affects the sound quality (it is very clearly audible). If Roon is processing the stream to alter volume, does n’t that affect the sound quality/resolution also?

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Hi Whatu1tme2b,

• Roon uses 64‑bit floating‑point DSP
This gives ~300 dB of mathematical dynamic range — far above what any DAC or amp can reproduce.
The Attenuation does not lose resolution or add noise.

• All gain changes are combined into ONE calculation
Headroom + Volume Leveling are merged into a single multiplier.
So no stacked stages, no cumulative distortion.

• Lowering digital level reduces noise, it doesn’t increase it
The DAC receives a cleaner, lower‑level signal that stays fully intact.
In my case no penalty, even at –20 dB or more.

I would try it out if you can.

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I assume that the actual bit stream needs to be changed to support lowering of the volume? It would no longer be bit-perfect. Or does n’t it work that way?

The variable volume mode on a Naim streamer does affect resolution and sound quality. Just wondering why digital volume control implemented in the Naim firmware would affect sound quality and the same functionality in Roon would not. Are these two completely different implementations?

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I’m getting a bit outside my knowledge zone here, but this is what I’ve learned so far.

Allegedly, Roon converts every audio sample into a 64‑bit floating‑point number and applies DSP by mathematically multiplying each sample with the attenuation factor (from Volume Leveling and Headroom). Because all processing happens in this very high‑precision digital domain, the output remains bit‑perfect relative to the adjusted signal. So as example: 1.00, 0.50, -0.30, 0.10 becomes 0.316, 0.158, -0.095, 0.0316. same curve, timing, detail, only lower in volume.

That’s what I’ve gathered from reading and asking around, so that’s why I’m checking here in the forumm.

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I am going to read a bit more about Roon. But I doubt this is something for me. The monthly subscription fee, the need for a dedicated Roon Core (I do n’t want to continuously run it on my laptop) etc.

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Still experimenting with the headroom settings. I’ve now reduced it to 10 dB and will continue to fine‑tune from here. The improvement in sound quality and detail is significant. Almost makes me wish I’d done this much earlier—slightly frustrating in hindsight.

It also feels a bit odd that the NDX2 outputs such a high voltage, effectively pushing the 252 to operate in its lower volume range. Hopefully someone at Naim takes note and considers addressing this in future updates or models.

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Naim have moved on from the Alps volume pot used in their Classic preamps, which was the cause of the low level channel imbalance problem in many systems. As you have discovered, it was designed for vinyl replay, and only became a problem when CD players arrived, with a much higher output level of around 2V. The New Classic preamp that replaced the 252 doesn’t have this problem.

When I had a 282 I used a separate DAC as an upgrade to my NDX2. It was a Chord DAC with a well implemented digital volume control which I used to dial down the level to suit the 282. For me there wasn’t a channel imbalance (not all of these volume pots had it) but it was frustrating to have to alter the volume by making such minuscule adjustments, and I thought the sound quality was improved by running the preamp at a higher level.

I used Roon for some time, but found that its sound quality was consistently inferior to using a UPnP server or streaming directly from Tidal or Qobuz.

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Thanks Chris, that’s a very clear explanation on the volume pots — I wasn’t fully aware of the historical background with the Alps and the higher output levels from CD players. That helps put things into perspective.

On UPnP:
I have to stick with Roon for now, as I don’t have a UPnP setup running, and in any case it wouldn’t really help with the volume‑pot behaviour I’m trying to address.

So far I’m very happy using digital attenuation in Roon**.** It gives me much better control on the 252, and the sound remains consistent. I’m still working through my digital/CD collection, but up to now I’m quite enthusiastic about the results.

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Hi, I have XS3 and ND5XS2 and can’t play much above 7-30 to 8 on the volume dial. Where did you obtain an attenuated cable and what are the specs. I already use Roon to get a better balance between the speakers, but maybe a cable would be a better solution!

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Hi, I bought a Russ Andrews cable: DIN PBJ Type E, 5 pin 180 to 5 pin 180, -14dB attenuation. I am very happy with that solution. You could even go higher on the attenuation.

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The ‘free’ solution is to turn on levelling in Roon at (say) -23LUFS, turn up the gain on the XS3, and see what it sounds like. If you want to get a bit scientific about it, use a sound level meter app on your phone to level match. You don’t need absolute accuracy, just be consistent how you measure.

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Very interesting solution you have there! I didn’t even know of attenuated cables until your post. My 282 also suffers from imbalance at very low volumes so I am considering this cable. Is there no loss in quality with this attenuation? And why did you chose the - 14 dB. That’s quite a big figure right? But I also see that on their website they go much higher. Up to 22 dB. So maybe it’s not that high

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I have not noticed any adverse effect on sound quality. It actually sounds better and that is most likely due to the higher volume on the amplifier. The volume control used to be extremely sensitive in the lower regions, but now I have much more control. The balance issue is solved. The -14dB was a bit of a gamble, based on other posts I read. Some people are using Rothwell in-line attenuators instead.

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Don’t forget that expectation bias works both ways…

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Reflections After a Few Days of Thinking About the Gain / Headroom Issue

I am genuinely flabbergasted (and that’s an understatement of 2026) that a Naim 252 (bought mine in 2018) or 282 (or others mentioned above) would require either a digital workaround (such as Roon volume leveling) or an analog workaround (such as an attenuator cable) simply to place the volume control in its optimal operating range.

The fact is that high‑output digital sources—especially CD players delivering 2V RMS—have been widespread since the mid‑1980s. This is not new, surprising, or unpredictable. Higher input voltages have been standard practice for decades, and with that in mind I would have expected Naim to address this in the design of their preamps much earlier than they eventually did.

For a company so strongly committed to musicality, purist engineering, and gain integrity, it feels strange that owners of such high‑level equipment still need to rely on external compensations just to achieve a proper gain structure. This is something that should have been anticipated and solved at the product level, not left to third‑party digital tools or add‑on hardware.

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Naim always argued that they chose the Alps volume pot because it sounded best despite its shortcomings, so I guess their commitment was to musicality rather than “gain integrity”. Yes, it took them a long time to produce alternative designs.

The extent to which this is a problem varies hugely between different systems. Those using only vinyl won’t have a problem, and those using fixed output digital sources will have widely differing experiences depending on loudspeaker efficiency, room size and preferred listening levels. For me it was irritating until I started using a non-Naim DAC with a variable output; at the time I had efficient speakers in a smallish room and often had the volume set low. Others posting here couldn’t understand the problem.

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Out of curiosity, what dimensions are the room? If you manage to get your distances as you described, that doesn’t suggest particularly small!. Re sound levels at the listening position, then that is simply your preference and nothing to do with room size, the only difference room size makes, or rather listening distance, is the volume control setting to achieve your desired sound level.

The problem is that the gain of the Naim preamp is too high - though I don’t think Naim is alone in this - with a digital signal attenuation is needed with no gain, electronics needing only to provide input and output buffering if necessary and suitable source and sink impedances, and possibly bandwidth limiting to prevent problems in the power amp. My own DAC has a volume control that doesn’t adversely affect sound quality, and as a consequence I don’t use a preamp at all with digital sources, simply feeding DAC output direct to power amp. (THe DAC’s output stage is a very capable one, happy with a very wide range of load impedances, and if ultrasonic filtering is required it can do)