Which kind of source does Rob recommend feeding a Chord DAC?

The practical answer

Make sure the data is bit perfect. His source advice assumes it. In February 2024 he wrote that his comparison "assumes bit perfect data that has not been processed in any way" Head-Fi, Feb 2024.

A phone or a battery laptop is his reference source. In September 2020 he wrote "Your phone is the best source you can get technically if you have bit perfect data using the phones local memory", because it is low power and battery operated, so no RF currents can circulate into the DAC ground plane Head-Fi, Sep 2020. His advice then was to use the phone as a reference and pick a streamer that sounds close or identical to it Head-Fi, Sep 2020. In December 2022 he wrote "Use a mobile phone, or a battery powered laptop as your reference source, with of course an app that provides bit perfect data" Head-Fi, Dec 2022.

Optical is the reference connection. In December 2022 he called optical "the best digital connection" and wrote "USB can sound as good as optical, but it depends upon how noisy the source is" Head-Fi, Dec 2022. For Mojo 2 he wrote in February 2024 "Optical with my DACs is the reference sounding source in that jitter doesn't matter", and said a phone or battery-powered player connected to Mojo 2 should sound the same as optical Head-Fi, Feb 2024. He repeated "Optical is the reference" in the Mojo 2 thread in August 2024 Head-Fi, Aug 2024.

Be wary of extra boxes. In March 2021 he wrote "Adding extra boxes will almost certainly degrade the sound by increasing overall RF" Head-Fi, Mar 2021. In 2018 he said the servers and reclockers he had heard "all sounded brighter with poorer depth" Head-Fi, Sep 2018.

If you hear no difference, stop worrying. In March 2021, after suggesting a phone with a bit-perfect app as a check, he wrote "If your source sounds identical, or close to identical, then don't worry about the source from a SQ POV" Head-Fi, Mar 2021. For Dave in 2020: if a desktop PC sounds the same as a laptop on batteries, "you are good to go" Head-Fi, Aug 2020. He calls these differences small: for Dave in 2016, laptop battery versus mains was "in my bottom scale of SQ differences" Head-Fi, Aug 2016, and in 2018 "we are talking tiny differences" Head-Fi, Jan 2018.

By product

• Hugo (2014): "Hugo just sounds like Hugo whatever the source", though not from AB tests Head-Fi, Apr 2014.
• Hugo 2 (2017 to 2018): he heard no change between his MSI laptop's optical and USB outputs, said that depends on the source, and advised optical as the benchmark: "the source that gets closer to the sound of optical is the best one" Head-Fi, Dec 2017Head-Fi, May 2018.
• Mojo and Hugo 2 (CanJam NYC 2022 Mojo 2 seminar, video published March 2022): he is transcribed saying "Mojo and Hugo 2 does not have galvanic isolation", that quiet sources are fine, and "On very noisy servers, you will not be perfectly fine" MFG Audio Reviews 56:58.
• Qutest (2019): "assuming bit perfect data, the source can only change the sound by adding RF noise into the DAC", so simpler and lower power is better Head-Fi, Feb 2019; and "sources still do make a difference" Head-Fi, Mar 2019.
• Dave (2018 to 2020): a laptop connected to nothing but Dave's USB port gives the lowest possible RF noise into Dave Head-Fi, May 2018. The best-sounding source may come "from a streamer. Or an isolated lap-top" Head-Fi, Aug 2020.
• Hugo TT2 (October 2022): on his MSI laptop running on battery, USB "sounded absolutely identical to optical"; where you can hear a difference, he would stick with optical Head-Fi, Oct 2022.
• Blu 2 (2018): reports he had seen put CD replay on the Blu 2 ahead of a dedicated server, which he put down to lower power and RF noise Head-Fi, Aug 2018.

Streamers

In November 2021 he wrote he would not spend design time on streamers because "all a DAC needs is bit perfect data" Head-Fi, Nov 2021. In February 2023 he said different streamers currently sound different on his DACs, and that his job is to make source choice not matter Dusty Audio 48:52. In a talk published in May 2026 (recording date not stated) he said he is not working on a streamer and intends very poor and very good streamers to sound the same Audio Force 18:19. He does not recommend a streamer brand or model in this archive; when an owner's Lumin U2 came up in 2023, he suggested trying its optical output Head-Fi, Nov 2023.

One change

For Dave in 2016 he wrote that USB "has slightly better timing as the source clock is Dave's local clock" Head-Fi, Aug 2016. By January 2018 he wrote "I used to think that USB had the edge on optical" and "I was wrong about that" Head-Fi, Jan 2018. In February 2019, in the Qutest thread, he still wrote "Technically USB is better from the clock POV" while saying "in practice I have had optical sound identical to USB" Head-Fi, Feb 2019. In March 2022 he called his 2016 preference for USB a mistake Head-Fi, Mar 2022, and in October 2022 he wrote "there is no technical benefit to using USB over optical when using my DACs" Head-Fi, Oct 2022, which differs from his February 2019 wording.

Quotes

“Your phone is the best source you can get technically if you have bit perfect data using the phones local memory”2020-09-20 Head-Fi, Sep 2020

“Use a mobile phone, or a battery powered laptop as your reference source, with of course an app that provides bit perfect data.”2022-12-13 Head-Fi, Dec 2022

“keeping your source as simple as possible is the best bet.”2021-03-07 Head-Fi, Mar 2021

“Optical with my DACs is the reference sounding source in that jitter doesn't matter”2024-02-29 Head-Fi, Feb 2024

Dated positions

Caveats and open points

• He repeatedly says results depend on how noisy a given source is and that his listening is limited to the sources he has tried.
• He does not recommend a streamer brand or model in this archive. In 2023 he named an owner's Lumin U2 only to suggest trying its optical output Head-Fi, Nov 2023.

Topics: Source devices, streamers and networks, Choosing and comparing inputs