Do Chord DACs need burn-in or warm-up?

Watts separates three things: physical (hardware) break-in, "brain break-in" (the listener adapting to a new sound), and warm-up after switching on Head-Fi, Mar 2017Head-Fi, Sep 2018. His statements on each are below, by period. Each statement below is tied to the product he was discussing; one product's statement is not carried to another unless he said so.

Physical burn-in

2014: original Hugo

In April 2014 he said Hugo kept sounding better the more he listened ("I swear it sounds better now than then"), that he did not know whether this was Hugo breaking in or his brain, and that listening tests of old against new units did not show a big difference Head-Fi, Apr 2014. In October 2014 he wrote "My designs do not have a big break-in period", explaining that he designs to reduce sensitivity to component aging, and that "Hugo does have a break-in, but this is more due to one getting used to the sound - breaking in your brain if you like!" Head-Fi, Oct 2014.

2016: 2Qute and DAVE

In January 2016, comparing 2Qute with Hugo on optical or coax, he said "2 Qute needs more breaking in and should be left on" Head-Fi, Jan 2016. It is the only statement found in the archive where he says a Chord DAC of his needs more break-in; he gave no figure or reason Head-Fi, Jan 2016.

In March 2016 he said that about 25 years earlier his DACs "had big break-in periods", that he worked through many design iterations to reach "minimal break-in period", and that "Today, brain break-in is by far the biggest variable." Head-Fi, Mar 2016. He gave the example that electrolytic capacitors take 3 months for impedance and leakage current to fall, and said the fix is to design the circuit so that does not matter Head-Fi, Mar 2016.

His 2016 statements on DAVE range from unsure to doubtful about physical break-in, without a firm claim either way Head-Fi, Mar 2016Head-Fi, May 2016Head-Fi, Jun 2016. On 30 March he was "not 100% sure" it had much break-in, and described a production code update that seemed to keep improving for 8 weeks on a unit with thousands of hours, which he said "can't be physical break-in", adding "Maybe brain break-in, but perhaps not." Head-Fi, Mar 2016. On 21 May he wrote that "my honest answer is I do not know for sure, except that brain break-in is by far the biggest factor" Head-Fi, May 2016. On 16 June: "I would be very surprised if Dave did have any significant break in", while listing the mechanisms behind the break-in his own products suffered in the 1980s and early 1990s (temperature-dependent distortion, electrolytic capacitors that "often need 90 days on", RF noise) Head-Fi, Jun 2016. He also said the small filter capacitors in DAVE's signal path are polypropylene and do not break in Head-Fi, Jun 2016.

In July 2016 he compared a brand new DAVE with his pre-production unit. The new one was "a bit brighter" and more transparent; he tentatively put that down to hand soldering on the prototype, and concluded that "brain break-in is way more important than physical break-in" Head-Fi, Jul 2016. In the same post he said "I suspect that the new unit will sound slightly smoother with time" Head-Fi, Jul 2016; later that day he wrote "With Dave, I have no evidence that it will get smoother or warmer with time - and I suspect that if it does change, it is small." Head-Fi, Jul 2016. In February and October 2016 he also said DAVE should sound good "straight out of the box" given a transparent system Head-Fi, Feb 2016Head-Fi, Oct 2016.

2017 to 2020: Hugo 2, Qutest, M Scaler, TT2

• Hugo 2. In March 2017: "I have never heard any warm up or break-in time with Hugo 2" Head-Fi, Mar 2017, and "Short answer - no burn in time needed - except for the first full charge." Head-Fi, Mar 2017. He said units from the same prototype batch "sounded and measured identically", and that Hugo 2 has no AC coupling capacitors in the signal path and does not rely on electrolytic capacitors in the power supply Head-Fi, Mar 2017. In June 2017 he said improvement over time with Hugo 2 is "almost certainly to be brain break-in" Head-Fi, Jun 2017. In August 2020: "I haven't heard any change with new units against old units." Head-Fi, Aug 2020.
• Headfonia interview, December 2017. Asked whether he believes in the burn-in effect of electronics, he answered "Sure", calling it a useful way of finding problems, and said "When it has break-in, particularly when it is measurable, then you need to identify the cause and remove it." Doing that, he said, gives "no break-in or significant warm up too." article, Dec 2017.
• Qutest thread, May 2018. "Yes hardware burn in is for sure a real phenomenon, and something I have fought against for several decades." He said that in his current DACs "you will not get a change in measured performance at all, even when cold", that any perceived improvement over time is likely brain break-in, and that while his Hugo 1 still seemed to be improving 9 months in, a brand new unit sounded identical Head-Fi, May 2018.
• Prototype units, May 2018 (DAVE thread). In a post that also discusses Blu 2, he said he had had about 8 units on different prototype PCBs and never heard changes he could put down to hardware break-in, while changes heard a month into new code on old units he put down to brain break-in; he noted the new units "would have clocked up 8 hours or more before listening" because of measurements Head-Fi, May 2018. The post does not name which product the 8 units were.
• M Scaler, September 2018. "I didn't hear any hardware related break-in changes at all", "but that doesn't mean that there aren't any changes possible"; he saw no mechanism because the output drive does not rely on electrolytic or tantalum capacitors Head-Fi, Sep 2018.
• Hugo 2 thread, September 2018. Taking up the word "adamant", he wrote "Adamant is perhaps a strong word - lack of my own evidence is more appropriate!", and "But I would not say that for sure hardware break in has been entirely eliminated - just I haven't seen any evidence of it." Head-Fi, Sep 2018.
• TT2, October 2018. "I have no experience of hardware break-in"; his units "were broken in before listening with all the technical and measurement tests that I had to do", so it may sound better with time, but "I would be surprised if it was a big change" Head-Fi, Oct 2018.

2022 onward

In February 2022, in the Mojo 2 thread and speaking of his DACs generally: "My DACs do not have any significant warm up time, nor do they have a break-in period - any changes to SQ is your brain adjusting to the new sound." Head-Fi, Feb 2022. At CanJam SoCal in September 2022 he said "There's no break-in time" and that a change heard after buying "it's because your brain is getting used to it" The Source AV 42:02. At CanJam SoCal 2023 he described the goal that you "turn the unit on and it works and it sounds the same as an hour's time", added "that's a quality that the DACs do actually have", and said a variation tells the designer to find and remove its cause The Source AV 47:35The Source AV 48:50.

Brain break-in

He describes brain break-in as the main source of improvement owners hear over time Head-Fi, Mar 2016Head-Fi, May 2016Head-Fi, Feb 2022. In August 2016 he said he first experienced it with Hugo, linked it to the brain unlearning coping strategies for timing errors, and added "I stress this is only an hypothesis" Head-Fi, Aug 2016. In July 2016 he said it shows as better soundstage depth and better perception of the starting and stopping of notes, but "on smoothness, I have never heard anything that could be put down to brain break-in", so smoothness changes are hardware Head-Fi, Jul 2016. He has given these durations:

• 2016: about 75% of an improvement is heard immediately and the last 25% "takes a month or two" Head-Fi, Jul 2016.
• 2017, Hugo 2: "that will take typically about a month" Head-Fi, Mar 2017.
• 2018, M Scaler with TT2: "relax and listen to music for a week, so your brain can get used to the different way that music is reproduced" Head-Fi, Nov 2018.
• 2020, Hugo 2: "It can take a few weeks to adjust to a different sound." Head-Fi, Aug 2020.

Warm-up after switching on

2016 to 2022: usually about ten minutes, called small

His figure was not constant across products or years. In March 2017 he said "I have never heard any warm up or break-in time with Hugo 2" Head-Fi, Mar 2017, and in December 2017 he described the design goal as no break-in "or significant warm up" article, Dec 2017. The other statements give about ten minutes:

• DAVE, May 2016: "Stone cold, within 10 minutes the SQ is up to speed" Head-Fi, May 2016.
• Qutest thread, May 2018: "That said, the DAC does sound slightly warmer after being on for ten minutes" Head-Fi, May 2018.
• Hugo 2, September 2018: weight in the bottom end, which he called "more characteristic of hardware break-in", "happens with Hugo 2 on the first 10 minutes of warm-up" Head-Fi, Sep 2018.
• TT2, January 2019: "from un-powered it's about 10 minutes from a SQ POV" Head-Fi, Jan 2019. M Scaler with TT2, February 2019: "It just needs 10 minutes of warm-up!" Head-Fi, Feb 2019.
• January 2020: measurements show "absolutely no change" from switch-on to warmed up, but a small change in Hugo 2 sound after ten minutes "might be my ears and headphones settling down" Head-Fi, Jan 2020.
• September 2020, TT2 thread: "you get optimum sound quality within 10 minutes of powering up" Head-Fi, Sep 2020. The next day he said the ten-minute figure came from Mojo and Hugo 2, because "my Dave and TT2 are on all the time", called it "a pretty small change", and said it might have nothing to do with Hugo 2 Head-Fi, Sep 2020.
• February 2022, Mojo 2 thread: "My DACs do not have any significant warm up time" Head-Fi, Feb 2022.
• September 2022, CanJam SoCal, asked about 30 minutes: "It takes about 10 minutes. All the products take about 10 minutes." The Source AV 41:54. The figure comes; check the recording.

2023 to 2024: he withdraws it, on the strength of a Hugo 2 test

In January 2023 he said his warm-up experience came from portable DACs on flights, where things "sound a bit bright and flat in soundstage for the first 10 minutes", that "the DACs measure identically from cold", that "10 minutes for SQ warm-up with no break-in period is not something I worry about", and that "I rather suspect my issues are down to planes rather than anything else" Head-Fi, Jan 2023. In February 2023 he tested Hugo 2 with M Scaler from cold in a hotel room and "could not hear a significant difference on my opening track", concluding the 10 minutes was his ears and headphones adjusting to cabin pressure Head-Fi, Feb 2023. In March 2023 he said "there is no warm-up time on the scaler" (Hugo M Scaler) and repeated the Hugo 2 result Head-Fi, Mar 2023.

In January 2024 he said he "used to think" Mojo, Mojo 2, Hugo and Hugo 2 had about 10 minutes of warm-up, but a cold Hugo 2 at home showed "absolutely no warm-up time in terms of SQ at all" Head-Fi, Jan 2024. In the same post he said occasional reports of 30 minutes could be unit-to-unit variation, which he called unlikely, transducer behavior, or hearing changing over time Head-Fi, Jan 2024. In September 2024: "If you had asked me a couple of years ago I would have said all my DACs need 10 minutes to sound at their best", followed by "Absolutely no change in sound quality in warming up Hugo 2." Head-Fi, Sep 2024. Here he describes the change of view in his own words, and the 2024 wording covers "all my DACs"; the test he reports is on Hugo 2 (with M Scaler in the 2023 hotel test) Head-Fi, Feb 2023Head-Fi, Sep 2024. For DAVE he said in 2023 "I don't know about Dave as I always keep it on. But I can't say I have noticed a change when it's been off though." Head-Fi, Feb 2023.

Leaving units on

He said in 2014 and 2016 that he left his Hugo on because he was lazy, noting its low power draw Head-Fi, Jun 2014Head-Fi, Jan 2016. From 2020 he said he keeps DAVE and TT2 on all the time Head-Fi, Sep 2020Head-Fi, Jul 2020Head-Fi, Jul 2021, that electronics are more reliable left on Head-Fi, Jul 2021, and in 2021 that Qutest "was intended to leave it on permanently" Head-Fi, Oct 2021. Apart from the 2016 2Qute remark Head-Fi, Jan 2016, the reasons he gave for leaving units on were convenience, low power draw and reliability, not burn-in Head-Fi, Jun 2014Head-Fi, Jan 2016Head-Fi, Jul 2021Head-Fi, Oct 2021.

What he has not said: the archive has no statement giving a burn-in period in hours for any current Chord DAC, no reason for the 2016 remark that 2Qute needs more breaking in Head-Fi, Jan 2016, and no reported cold-start listening test of DAVE, TT2, Qutest or Mojo 2 after he withdrew the ten-minute figure Head-Fi, Feb 2023Head-Fi, Sep 2024. There is nothing from him on burn-in or warm-up for Quartet or other newer products.

Quotes

“My DACs do not have any significant warm up time, nor do they have a break-in period - any changes to SQ is your brain adjusting to the new sound.”2022-02-14 Head-Fi, Feb 2022

“But I would not say that for sure hardware break in has been entirely eliminated - just I haven't seen any evidence of it.”2018-09-21 Head-Fi, Sep 2018

“Short answer - no burn in time needed - except for the first full charge.”2017-03-26 Head-Fi, Mar 2017

“Absolutely no change in sound quality in warming up Hugo 2.”2024-09-25 Head-Fi, Sep 2024

Dated positions

Caveats and open points

• Most statements are about Hugo, DAVE and Hugo 2. His 2022 and 2024 statements are worded for all his DACs, but the cold-start retest he reports (2023 to 2024) was on Hugo 2, with M Scaler in one test.
• He has not reported retesting DAVE or TT2 from cold; he keeps them on all the time. For DAVE in 2023 he said he did not know, though he had not noticed a change when it had been off.
• The 2016 statement that 2Qute needs more breaking in has no stated reason or duration and was not revisited in the archive.
• The May 2018 post about 8 prototype units (Head-Fi, May 2018) does not name the product.
• His account of brain break-in is, in his words, only an hypothesis.

Topics: Burn-in, warm-up and brain break-in