Is battery power better than mains, and can I power the M Scaler or Qutest from a power bank?

His general position: the battery as reference

In a February 2019 summary for the M Scaler and TT2 he wrote: "Battery powering eliminates the issue, as no mains leakage currents or PSU/ground loops, and should be treated as the reference" Head-Fi, Feb 2019. He has repeated that a car battery is the best possible supply, citing its sub-milliohm impedance, high current, absence of noise and isolation from the mains, in posts from 2020 and 2022 and in talks in 2023, 2024 (there framed for power amps) and 2026 Head-Fi, May 2020Head-Fi, Nov 2022Soundnews 38:19Eric's Hi-Fi 12:36MFG Audio Reviews 38:19HiFi Buys 2:22:31. For low-power DACs and amps he said at CanJam NYC 2024 that lithium-ion batteries "are also ideal", and that "battery operation is always the ideal" against which a supply should be measured or heard MFG Audio Reviews 39:06MFG Audio Reviews 40:30. He uses car batteries and very large lithium-ion packs only for testing his supplies, not in everyday use (January 2025) Head-Fi, Jan 2025.

His stated reasons are mains RF noise and ground currents. In August 2018 he wrote that between 10 MHz and 10 GHz "a battery power bank is very much better than mains supply", and that disconnecting from the mains means no ground loops Head-Fi, Aug 2018. In October 2021 he said batteries have almost zero RF noise and that using one "will completely isolate you from mains random RF noise" Head-Fi, Oct 2021. He has defended power banks that use switch-mode converters: switching noise is easy to filter, and the benefit is the absence of mains-borne RF and full isolation (2018 and 2022) Head-Fi, Jun 2018Head-Fi, Feb 2022Head-Fi, Feb 2022.

He has qualified this. In June 2022 he wrote "As to current powerbanks I know that they are not perfect" and said he would not design one Head-Fi, Jun 2022. He found power-bank quality audible on the M Scaler: in January 2023 a Krisdonia unit sounded clearly worse than a Bixpower, which he attributed to the Krisdonia's voltage converter Head-Fi, Jan 2023. In a podcast recorded in October 2025 (published March 2026) he said "There are RF issues with batteries, but that's another question." ecoustics 1:08:48. Describing Quartet development in the same podcast, he said that at first "The mains power supply sounded better than the lithium ion battery." and that after adding shunt capacitors and RF cables to the battery hookup, "the battery was slightly better than the mains unit" ecoustics 1:11:12ecoustics 1:12:50. These come; check the recording.

The design goal: mains that sounds like a battery

Hugo TT (2015). He said the original TT used batteries to guarantee isolation from mains noise, because when the project began in 2014 Chord did not know how much of Hugo's sound came from its batteries; having since shown that more RF filtering and regulation gave battery sound quality, he wrote "So if TT was designed today, I would go for no batteries" Head-Fi, Feb 2015.

Qute family and Qutest. In 2016 to 2018 posts he said the original Qute sounded much better on a car battery, while 2Qute, with an extra regulation stage and more RF filters, showed no audible difference Head-Fi, Jan 2016Head-Fi, Dec 2017Head-Fi, Feb 2018. In February and March 2023 talks and in an interview published October 2026 he instead named 2Qute as the sensitive unit: in March 2023 he said he "was shocked with 2Qute" when he used a car battery; in February 2023 he first said "this Qutest" was sensitive and then "sorry, that was 2Qute"; and in 2026 he said the car battery "sounded dramatically better" Soundnews 39:49Eric's Hi-Fi 18:34HiFi Buys 2:21:42HiFi Buys 2:22:57. In every later account (2022 post, 2023 and 2026 interviews) the fix was made in Qutest, after which the supplied switch-mode supply sounded the same as a car battery Head-Fi, Mar 2022Soundnews 40:35HiFi Buys 2:22:57. The 2022 post names the original Qute, not 2Qute, as the sensitive unit Head-Fi, Mar 2022.

Hugo TT2. In June 2018 he wrote "What I wanted was battery SQ but mains powered", achieved with super caps and inductive filtering Head-Fi, Jun 2018. In a November 2018 open-day talk (uploaded December 2018) he said the supplied supply was chosen after testing several so that it matched a battery in sound and measurements Pursuit Perfect System 38:09. In 2019 he wrote that on TT2 you can unplug the supply, use the stock one, or use a battery bank, "and they all sound and measure the same" Head-Fi, Dec 2019.

In a June 2023 post in the M Scaler thread that does not name the product, he reported no sonic difference in his system between a PowerAdd power bank and the supplied SMPS, with zero measured difference in the audio band and a 0.5 dB degradation at a 100 kHz bandwidth, adding that the other supplies he tested when selecting the unit for TT2 measured poorly Head-Fi, Jun 2023. In a February 2023 talk he described the same TT2 supply selection, with the chosen unit showing a half dB degradation at 100 kHz bandwidth and sounding the same as a car battery Soundnews 41:34. In 2021 he wrote that replacing the TT2 supply with an isolated battery changed neither the sound nor, at wide bandwidth, the measurements Head-Fi, Jan 2021Head-Fi, Jun 2021.

Hugo M Scaler. His concern with the M Scaler is ground-loop current into the DAC, covered below. In March 2023 he said of TT2 and car batteries, "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.

Quartet (2024 to 2026). He has said Quartet's supply and input RF filtering make it behave as if battery powered, and in an interview recorded in autumn 2026 (published October 2026) that his target was sound as good as a large lithium-ion battery, "and I've succeeded in doing that" HIFICLUB 46:35AVstore 1:38article, Oct 2026.

DAVE. In January 2016 he said that given DAVE's internal regulation and filtering he "would be extremely surprised" to hear a battery difference, framing it as a test he had not run ("if I were to do such a test") Head-Fi, Jan 2016. At CanJam NYC 2024, asked why DAVE has no battery, he said "A battery in DAVE is a good idea" and that he would not design DAVE the same way today MFG Audio Reviews 56:32.

Qutest from a power bank

Yes, by his account. In January 2018 he said a supply meeting USB specifications would not void the warranty (after checking with Chord), that Qutest was "designed to be power supply immune", and that a battery-powered USB charger "would represent the ultimate PSU" Head-Fi, Jan 2018. He gave Qutest's draw as 2.5 W, so 100 Wh lasts about 40 hours, and said USB power was chosen partly because battery supplies are inexpensive Head-Fi, Jan 2018. He used a 100 Wh bank with 5 V/2.1 A output (April 2018) and later an 85 Wh PowerAdd Pilot Pro 2, about 35 hours on paper Head-Fi, Apr 2018Head-Fi, Oct 2018.

His advice has been to use the bank as a test: if a battery sounds the same as the supplied supply, a linear upgrade can only sound the same or worse (2018) Head-Fi, Jan 2018Head-Fi, Feb 2018Head-Fi, Mar 2018Head-Fi, May 2018. He reported different results at different times from his own system: "it sounds the same, but YMMV - it depends upon the rest of your system" (October 2018) and "My own listening tests revealed tiny differences by replacing the Qutest PSU with a battery" (March 2019), each with a YMMV qualifier Head-Fi, Oct 2018Head-Fi, Mar 2019. He said a bank also removes the capacitive mains loop of the supplied ungrounded supply, and suggested one for anyone worried about that loop (March 2019) Head-Fi, Mar 2019.

On voltage (December 2023): "It needs to be 5v +/-0.25v" (the USB standard); he said a USB power bank is safe because higher fast-charge voltages need a handshake Qutest does not send, and that more than 5 V would blow the input protection diode Head-Fi, Dec 2023.

Hugo M Scaler from a power bank

Voltage and current. He has said the M Scaler runs from 9 to 15 V and that he chose a 15 V maximum so a laptop battery pack could power it (November 2018 open-day talk, uploaded December 2018) Pursuit Perfect System 14:11Pursuit Perfect System 15:04. In July 2018 he wrote "Never go above 15V on the input with the Hugo M scaler." Head-Fi, Jul 2018. In November 2019, in the M Scaler thread, he wrote that 16 V could destroy the protection diode, in January 2020 that 18 V or more will destroy it, and in October 2020 and June 2022 that damage can start at 16 V; he has also said it needs only 1 A at 12 V, and that all inputs are regulated to 5 V internally, so the input voltage does not affect sound (2019 to 2022) Head-Fi, Nov 2019Head-Fi, Jan 2020Head-Fi, Sep 2020Head-Fi, Oct 2020Head-Fi, Jun 2022. In January 2025 he said a falling battery voltage as it discharges does not change sound quality Head-Fi, Jan 2025.

Warranty. In 2018 he wrote that Chord would deny warranty on a failure caused by a non-supplied supply, which is easy to detect because the protection diode fails Head-Fi, Jul 2018Head-Fi, Nov 2018.

Sound quality. His position here shifted from reporting no difference toward saying a battery breaks a ground loop into the DAC. In July 2018 he wrote that battery or supplied PSU "seems to make no difference to SQ" Head-Fi, Jul 2018. From November 2019 he described RF current near 2 GHz flowing in a loop from the mains through the M Scaler and BNC cable into the DAC's ground plane, and said an isolated power bank breaks that loop so BNC cables no longer affect the sound; in the same post he said he did not do this in practice because "the difference isn't large enough to bother with charging batteries" Head-Fi, Nov 2019. In a general January 2020 post, not tied to one product, he wrote that his aim was for mains powered, USB connected operation to match optical and battery, "and I am indeed getting there" Head-Fi, Jan 2020. In 2020 he wrote "The M scaler is helped by using a battery", that the M Scaler and DAC need separate supplies, and that the effect was "very much surface finish of the icing on the cake" Head-Fi, May 2020Head-Fi, May 2020Head-Fi, Aug 2020. He has said a power bank and Wave BNC cables are alternative fixes and only one is needed (2020 to 2023) Head-Fi, May 2020Head-Fi, Feb 2022Head-Fi, Jun 2023. In January 2023 he wrote that "the only way currently to guarantee 100% noise free operation is to have optical source and battery on the M scaler" Head-Fi, Jan 2023, and repeated in February 2024 that battery plus optical leaves no loop Head-Fi, Feb 2024. In 2022 he suggested grouping the source and M Scaler together on a battery Head-Fi, Feb 2022. He has said the bank must be isolated from the mains and ground, and that a bank sitting on a desk has low enough stray capacitance (2020) Head-Fi, Sep 2020Head-Fi, Sep 2020Head-Fi, Sep 2020. In July 2024, discussing Quartet, he recalled this BNC and source sensitivity on the M Scaler and said he had developed a supply with RF filters that gives "isolation as if it was a battery" HIFICLUB 45:42HIFICLUB 46:35.

Which bank. He used a PowerAdd Pilot Pro 2 set to 12 V, getting about 7 hours (2018) Head-Fi, Jul 2018Head-Fi, Oct 2018. In 2022 he preferred 9 V to 12 V on a Krisdonia, which he attributed to the Krisdonia Head-Fi, Jun 2022. From January 2023 he named the Bixpower BP90-12v, using its unregulated 12 V output, as the best he had heard, with nearly 10 hours of run time Head-Fi, Jan 2023Head-Fi, Sep 2023. In January 2025: "use the supplied PSU or if you want the absolute best then use the BixPower" Head-Fi, Jan 2025. In September 2023 he said he uses it only on flights, since at home the supplied PSU and Wave cables sound the same with optical input Head-Fi, Sep 2023; he has used a battery bank with the M Scaler on flights since 2018 c w 25:32. He has warned that banks of 100 Wh or more can be confiscated at some airports, naming Thailand and China Head-Fi, Oct 2018Head-Fi, Nov 2018Head-Fi, Jan 2020Head-Fi, Jan 2020.

Other products

TT2. He has consistently said TT2 does not benefit: "TT2 doesn't benefit from it anyway" (May 2020), and in June 2023 he heard no difference using a power bank Head-Fi, May 2020Head-Fi, Jun 2023. He said it does run on a battery bank of 85 Wh or more that supplies 3 A at 12 to 15 V, which by his arithmetic should give about 6 hours with headphones (June 2018), and over 7 hours on 100 Wh (January 2020) Head-Fi, Jun 2018Head-Fi, Jan 2020. A 12 V bank limits peak output voltage, which matters only above +7 dB (2019) Head-Fi, Aug 2019. If the M Scaler is on a battery, a second battery on TT2 adds nothing (2020) Head-Fi, Sep 2020. In February 2024 he suggested trying an isolated battery on TT2 as a test before changing its supply Head-Fi, Feb 2024.

Hugo 2 and Mojo 2. In January and August 2018 he said he could not hear or measure the effect of adding the supplied charger to Hugo 2 with headphones Head-Fi, Jan 2018Head-Fi, Aug 2018. In October 2021 he wrote "adding the charger to Hugo 2 can make it sound brighter" and recommended a power bank, recharged overnight, for desktop use Head-Fi, Oct 2021. He warned against powering Hugo 2 from a bank's adjustable DC output, since it can exceed 5 V; the USB outputs are fixed at 5 V (February 2022) Head-Fi, Feb 2022. On Mojo 2 (January 2022) he said "you're always going to get the best sound quality by having it purely battery", with desktop mode designed to minimize the loss Darko.Audio 16:39. For Mojo 2 desktop setups he has suggested disconnecting the charger as a test and using a power bank only if the difference is significant (June 2022, October 2026) Head-Fi, Jun 2022Distorsiuni Interioare 42:28.

Scope of his claims

He frames these as results from his own systems. In February 2018 he wrote that this "does not mean my observations will apply in all systems all of the time", and he often adds YMMV Head-Fi, Feb 2018Head-Fi, Feb 2019Head-Fi, Jan 2018.

What he has not said: this archive has no battery-versus-mains test of DAVE by him (his 2016 remark is a prediction) and no blind test results for any of these comparisons; he does not name a specific power bank for Qutest beyond the 100 Wh 5 V/2.1 A unit and the PowerAdd Head-Fi, Jan 2016Head-Fi, Apr 2018Head-Fi, Oct 2018.

Quotes

“What I wanted was battery SQ but mains powered, and with the supercaps, and the large inductive filtering, I have managed that.”2018-06-26 Head-Fi, Jun 2018

“Battery powering eliminates the issue, as no mains leakage currents or PSU/ground loops, and should be treated as the reference”2019-02-25 Head-Fi, Feb 2019

“My own listening tests revealed tiny differences by replacing the Qutest PSU with a battery - but that was with my setup so YMMV.”2019-03-17 Head-Fi, Mar 2019

“the only way currently to guarantee 100% noise free operation is to have optical source and battery on the M scaler”2023-01-08 Head-Fi, Jan 2023

Dated positions

Caveats and open points

• His sound-quality findings come from his own systems and listening, usually with a YMMV qualifier; he reports no blind tests for these comparisons.
• His accounts of which Qute-family DAC was supply-sensitive differ: 2016 to 2018 posts name the original Qute (2Qute was the fix); a 2022 post names the original Qute and puts the fix in Qutest; the February and March 2023 talks and the 2026 interview name 2Qute as the sensitive unit and Qutest as the fix (in the February talk he corrected himself mid-sentence from "this Qutest" to "sorry, that was 2Qute").
• Warranty statements are Watts relaying Chord policy; readers should check Chord's current written terms.
• Power-bank models he named (PowerAdd Pilot Pro 2, Krisdonia NJF-2, Bixpower BP90-12v) reflect what he used at the time; he said the PowerAdd was no longer available by 2023. Airline limits are his own travel experience, not a rule he states.
• The M Scaler ground-loop benefit applies when the M Scaler feeds a separate DAC; he describes it as small and says Wave cables or Quartet address the same issue.
• A June 2023 power-bank comparison (Head-Fi, Jun 2023) does not name the product; its reference to selecting the TT2 supply and the matching 2023 talk suggest TT2, so it is not presented as an M Scaler result.

Topics: Power supplies and battery packs, Ground loops, galvanic isolation, earthing and mains