Should I replace the supplied power supply with a linear or aftermarket one, and will that affect my warranty?

Sound quality: his general position

Across 2018 to 2024 Watts has argued that audiophile linear supplies lack the RF filtering a switch-mode supply needs to meet EMC rules, so they pass random RF noise from the mains, which he links to noise floor modulation and a brighter sound that can pass for extra transparency Head-Fi, Mar 2018Head-Fi, Dec 2018Head-Fi, Sep 2020Head-Fi, Feb 2022MFG Audio Reviews 33:55. In 2018 he warned "Do not assume that a LPSU is lower in RF noise" Head-Fi, Feb 2018. He also cites mains hum and ripple, stray magnetic fields and higher transformer coupling capacitance as linear-supply drawbacks Head-Fi, Jul 2020Head-Fi, Mar 2022Soundnews 33:28MFG Audio Reviews 37:31. His stated reason for shipping small wall supplies, asked by What Hi-Fi? in March 2022 why Chord uses "cheap wall-wart power supplies": the units have internal regulation and RF filtering, and "Adding ‘better’ power supplies will either make no difference or make it sound worse (brighter)" article, Mar 2022article, Mar 2022article, Mar 2022.

He frames this as his own listening and his own systems. In 2018 he wrote that his experience "does not mean my observations will apply in all systems all of the time", attributing differences other people hear mainly to the PSU affecting other parts of their system, plus placebo Head-Fi, Feb 2018. He has also conceded the supplied supply could interfere with a sensitive power amp, "so this is a clear case of YMWV" Head-Fi, Jan 2018. In 2022 he wrote that his aim is for his designs to show no change in sound when a linear supply is attached, and that "As to current powerbanks I know that they are not perfect" Head-Fi, Jun 2022. His repeated test is to compare the supplied unit against a battery (or, on TT2, against no supply for ten seconds): if there is no difference, he says a linear supply can only sound the same or worse Head-Fi, Mar 2018Head-Fi, May 2018Head-Fi, Feb 2024MFG Audio Reviews 40:30.

By product

Hugo (2014). He told owners not to use anything but the supplied charger: "there is no benefit in sound quality with using other chargers, and there is a risk of damaging Hugo in using other PSU's" Head-Fi, Jul 2014. He had reported a month earlier that in AB tests he "could not hear a significant difference" with the charger plugged in or out Head-Fi, Jun 2014. He warned a 12.8 V battery supply may damage Hugo's input protection Head-Fi, Jul 2014.

Hugo 2 (2017 to 2022). In March 2017 his answer to a bigger external supply was "Absolutely not", saying external PSUs would "categorically" sound worse or make no difference Head-Fi, Mar 2017. In October 2017 he wrote "As to changing the supplied PSU with a linear one, then with headphones don't bother" Head-Fi, Oct 2017, and in 2018 he could not hear the charger plugged in or out on headphones Head-Fi, Mar 2018Head-Fi, Aug 2018. Later he qualified this: in October 2021 he said "adding the charger to Hugo 2 can make it sound brighter" and recommended a battery power bank for desktop use Head-Fi, Oct 2021, and in June 2022 he described the Hugo 2 charger as "a simple generic one with the simple intent of charging the battery" Head-Fi, Jun 2022. In February 2022, asked whether a linear supply with RF filtering at both ends would be clean enough for Hugo 2 or Mojo 2 in desktop mode, he answered "Probably not" and said "A power bank would still very much be preferable" Head-Fi, Feb 2022. He warned that a power bank's adjustable DC output could exceed 5 V: "That would damage Hugo 2 protection diodes." Head-Fi, Feb 2022

2Qute and Qutest (2016 to 2026). His account of which product was sensitive has shifted. In 2016 to 2018 he wrote that the original Qute was sensitive to its supply and that on 2Qute, with an added regulation stage and RF filters, a car battery made no difference: "I could not hear a difference at all (unlike with Qute where there was a big difference)" Head-Fi, Jan 2016Head-Fi, Dec 2017Head-Fi, Feb 2018. In 2022 he wrote that "the Qute DAC was sensitive to the PSU" and that he fixed it on Qutest Head-Fi, Mar 2022. In 2023 and 2026 interviews he names 2Qute as the sensitive unit and Qutest as the fix; in the February 2023 one he first says Qutest, then corrects himself: "sorry, that was 2Qute" Soundnews 39:49Eric's Hi-Fi 18:34HiFi Buys 2:21:42HiFi Buys 2:22:57. For Qutest itself, he said in 2018 it was designed to be "power supply immune" and that "A USB battery pack will outperform a linear PSU as it eliminates RF noise from the mains." Head-Fi, Jan 2018Head-Fi, Jan 2018. In May 2018 he said "the supplied PSU is as good as a battery supply" in his set-up Head-Fi, May 2018; in March 2019 he reported "My own listening tests revealed tiny differences by replacing the Qutest PSU with a battery - but that was with my setup so YMMV" Head-Fi, Mar 2019. In 2021 he read a user's reported gains from an aftermarket Sbooster supply as signs of added noise floor modulation Head-Fi, Jan 2021. In a 2023 interview he said the Qutest supply sounds the same as a 12-volt car battery Soundnews 40:35.

Hugo TT 2 (2018 to 2024). His most consistent case. He says the real PSU is internal (input inductor, super-caps, RF filtering and regulation), that TT2 runs for about ten seconds with the brick unplugged, and that he heard no change doing so Head-Fi, Jan 2019Head-Fi, Aug 2019Head-Fi, Jul 2020Head-Fi, Mar 2021. In June 2018: "A linear PSU will almost certainly make it sound worse, as the audiophile ones have no RF filtering, unlike the supplied PSU." and "So absolutely not recommended." Head-Fi, Jun 2018. He says the brick was chosen from many tested units because it measured like a battery in wide-bandwidth tests and is not earthed Head-Fi, Dec 2018Head-Fi, Apr 2020Head-Fi, Jul 2020Head-Fi, Nov 2020. In a June 2023 M Scaler thread post comparing a power bank with the supplied SMPS he qualified the measurement claim: "zero difference on the measurements in the audio bandwidth" but "a negligible 0.5dB degradation with a 100kHz bandwidth", with no sonic difference in his system Head-Fi, Jun 2023. In January 2021 he summarized: remove the supply for ten seconds or substitute an isolated battery and there is "no difference in sound quality", while an audiophile linear supply changes the sound through added RF noise Head-Fi, Jan 2021. In 2020 he clarified: "I have never said that LPS would not change the sound quality; they just sound worse in my opinion" Head-Fi, Jul 2020. In 2021 he kept the caveat "Of course, this is with my system, and your mileage may vary." and admitted "What I should have done was to use a great deal more RF filtering" so a linear supply would make no difference at all Head-Fi, Jun 2021. His latest forum statement (February 2024): "Using LPS on TT2 would be a downgrade", with the advice to try an isolated battery first Head-Fi, Feb 2024. In a 2023 interview he added that with TT2 "You can't hear a difference when you're using a car battery, unless you're using an M Scaler." Eric's Hi-Fi 19:18.

Hugo M Scaler (2018 to 2025). He found no difference between battery and supplied PSU in 2018 and said "No don't bother with a linear PSU - they do not employ RF filters, so are not as capable as the supplied PSU." Head-Fi, Jul 2018Head-Fi, Sep 2018. The M Scaler supply was sourced from the TT2 project; he says grounded supplies measured worse because of ground loops Head-Fi, Sep 2018Head-Fi, Nov 2018. His M Scaler concern is GHz-range current flowing through the loop from mains to M Scaler to DAC; he says an ungrounded, RF-filtered SMPS helps and a linear one hurts Head-Fi, Nov 2019Head-Fi, Apr 2020. Unlike TT2, he says "The M scaler is helped by using a battery" Head-Fi, May 2020, with an isolated power bank or ferrite (Wave) BNC cables as alternative fixes Head-Fi, Jun 2023, but in 2019 he described battery power for this purpose as small: "Is this something I do in practice - no" Head-Fi, Nov 2019. In January 2025 he advised: "use the supplied PSU or if you want the absolute best then use the BixPower" (a power bank) Head-Fi, Jan 2025. He has said power banks differ: one Krisdonia unit "sounded noticeably worse" than BixPower or PowerAdd Head-Fi, Jun 2023. In 2024 he compared an iFi supply's noise figure unfavorably with TT2's noise floor Head-Fi, Jun 2024.

DAVE (2016 to 2023). He has hedged most here. In 2016 he wrote "Would using a better SMPS give better SQ? Maybe, but the evidence suggests no." Head-Fi, Aug 2016, and said he would be "extremely surprised" to hear a difference with a car battery given DAVE's internal regulation Head-Fi, Jan 2016. In 2021: "I don't recommend changing the PSU, you will invalidate the warranty." Head-Fi, Apr 2021. In 2023 he said "I haven't done the battery tests with Dave" because its supply is more complex, while saying he is "happy intellectually" with DAVE's RF filtering Soundnews 43:18Eric's Hi-Fi 20:03.

Quartet M Scaler (2024 to 2026). Quartet ships with a separate supply Watts says he designed, with RF filters of over 200 components on the supply's output and on Quartet's input ConvinceMeAudio 2:12article, Jun 2024ecoustics 1:10:38. He said in 2025 that "only the supplied unit will give the required performance" Head-Fi, Jan 2025, in February 2024, of two then-unannounced products the post does not name, that "The PSUs are my own design" and "no doubt people will seriously degrade the performance by adding other PSUs" Head-Fi, Feb 2024, and in a talk published March 2026 (recording date not stated) that "it won't be possible for people to upgrade the power supply" Audio Force 26:36. In a podcast recorded in October 2025 (published March 2026) he described Quartet's mains supply at first sounding better than a 24-volt lithium-ion battery, which he traced to the battery's RF decoupling and cabling; after adding shunt capacitors and RF cables, "the battery was slightly better than the mains unit" ecoustics 1:11:12ecoustics 1:11:58ecoustics 1:12:50.

Mojo 2 (2022 to 2026). He said "In most circumstances it won't matter, you can use any charger", with a power bank as the fix if disconnecting the charger changes the sound Head-Fi, Jun 2022. In a January 2022 podcast he said there is "a slight loss by physically connecting something to the mains via the charger" and "you're always going to get the best sound quality by having it purely battery" Darko.Audio 16:39, and in October 2026 that "nobody has commented on sound quality losses by using it with the charger" Distorsiuni Interioare 42:28.

Warranty

His warranty statements are relayed Chord policy, not his own: he has written "I am merely the designer, so this is by no means an official answer" about warranty handling Head-Fi, Oct 2018. His wording has varied rather than moving in one direction: the broad "invalidated" form appears in 2019, the narrower over-voltage reading in September 2020, and the broad form again in 2021 and 2022.

• January 2018, Qutest (USB-powered): "If the attached PSU meets USB specifications then you will not void the warranty - I just checked with Matt from Chord about this." Head-Fi, Jan 2018. He later gave the spec as "It needs to be 5v +/-0.25v - the USB standard." Head-Fi, Dec 2023.
• July 2018, M Scaler: other supplies "may invalidate the Chord warranty in that if failure is down to overvoltage from the not supplied PSU then you would not be covered for that particular repair", and "The warranty with other PSU's applies to all Chord devices." Head-Fi, Jul 2018. November 2018: "Chord would deny the warranty if the failure was down to the use of the non-supplied PSU." Head-Fi, Nov 2018, and "Chord have updated their warranties as there are some audiophile PSU's that are unregulated and completely not fit for purpose." Head-Fi, Nov 2018. He says such failures are easy to detect because the protection diode fails Head-Fi, Nov 2018Head-Fi, Apr 2020.
• October 2019, TT2: "Don't think about using audiophile linear PSUs, they will degrade the SQ and your warranty will be invalidated." Head-Fi, Oct 2019. June 2020, Qutest: "Not using the stock PSU invalidates the Chord warranty, so this is very much at your risk." Head-Fi, Jun 2020.
• September 2020, TT2: "For sure you will invalidate the warranty also" Head-Fi, Sep 2020, then, in a follow-up post the same day that opens "Yes it does.", "In practice that means that over voltage faults that require service will not be covered by the warranty" Head-Fi, Sep 2020.
• April 2021, DAVE: "you will invalidate the warranty" Head-Fi, Apr 2021. July 2022, in the M Scaler thread, his most recent and broadest wording: "So using any PSU apart from the supplied units will invalidate Chord's warranty." Head-Fi, Jul 2022.

Voltage limits he has stated: never above 15 V on the M Scaler input Head-Fi, Jul 2018Head-Fi, Nov 2018; TT2 and M Scaler trip a power-high error above 15.5 V Head-Fi, Oct 2019; 18 V and above destroys the M Scaler protection diode (January 2020) Head-Fi, Jan 2020; in October 2020 he said damage can be done at 16 V and above Head-Fi, Oct 2020, and in June 2022 that "16v could cause damage to the unit" Head-Fi, Jun 2022.

What he has not said: he does not endorse any named linear supply, and does not reconcile his 2020 "over voltage faults" reading with his 2022 "any PSU" wording Head-Fi, Sep 2020Head-Fi, Jul 2022. Chord's own terms are on its warranty policy page. For DAVE he has said he has not run battery comparisons Soundnews 43:18.

Quotes

“there is no benefit in sound quality with using other chargers, and there is a risk of damaging Hugo in using other PSU's”2014-07-10 Head-Fi, Jul 2014

“A linear PSU will almost certainly make it sound worse, as the audiophile ones have no RF filtering, unlike the supplied PSU.”2018-06-24 Head-Fi, Jun 2018

“I have never said that LPS would not change the sound quality; they just sound worse in my opinion”2020-07-04 Head-Fi, Jul 2020

“So using any PSU apart from the supplied units will invalidate Chord's warranty.”2022-07-21 Head-Fi, Jul 2022

Dated positions

Caveats and open points

• Watts is the designer, not Chord: his warranty statements relay Chord policy, and in a 2018 post about warranty repairs he called his answer "by no means an official answer" Head-Fi, Oct 2018; Chord's current written terms are on its warranty policy page.
• His warranty wording is not a single progression: 'invalidated' in 2019 (TT2) and 2020 (Qutest), 'over voltage faults ... will not be covered' in September 2020 (TT2), 'invalidate' again in 2021 (DAVE) and 'any PSU apart from the supplied units' in 2022 (M Scaler thread); he has not reconciled them.
• His accounts of which Qute-family DAC was supply-sensitive differ: 2016 to 2018 posts say the original Qute, fixed in 2Qute; 2022 says Qute, fixed in Qutest; 2023 and 2026 transcripts say 2Qute, fixed in Qutest.
• His sound-quality claims are from his own systems and he repeatedly qualifies them with YMMV.
• Head-Fi, Feb 2024 (February 2024) refers to two then-unannounced products without naming them; it is placed under Quartet by context only.
• The Hifistatement Quartet interview is the publisher's German translation of English answers; it is cited for substance, not quoted.

Topics: Power supplies and battery packs, Faults, repairs, warranty, safety and updates