Source devices, streamers and networks

Inputs, sources, cables and clocking

Answers on this topic

• Do lossy or streamed files sound worse than local files on a Chord DAC?
• If the data reaching the DAC is bit perfect, can the source (laptop, phone, streamer, CD transport or network gear) still change the sound?
• Is Rob a Chord employee, and which Chord products (Poly, 2go, the amplifiers) did he not design?
• Which kind of source does Rob recommend feeding a Chord DAC?

Everything he said on this topic (102)

One-line summaries in our words, oldest first. Each link opens the original.

• 2014-04-17Watts says he has not tried many sources, uses a regular laptop on the go, and finds Hugo sounds like Hugo whatever the source, though not from AB tests. Head-Fi, Apr 2014
• 2014-06-19Watts says he is about to test USB isolators, aims for Hugo to work with any bit-perfect source, uses regular USB cables in his office and optical at home. Head-Fi, Jun 2014
• 2014-10-12Watts says his Olimex tests used a noisy Dell, so an iPhone may need no isolation; smoother sound and better depth indicate lower RF and correlated noise. Head-Fi, Oct 2014
• 2014-10-12Watts says he has no specific source recommendations, uses his laptop when traveling, and is deciding between a new phone, tablet or smaller laptop. Head-Fi, Oct 2014
• 2014-10-27Watts notes optical runs only to 192 kHz, some transmitters to 96 kHz, and says low-power mobile sources suffer far less from the noise problem than PCs. Head-Fi, Oct 2014
• 2014-10-28Watts says USB 5V only detects a connection and powers the HD USB chip with RF decoupled, USB-to-optical converters should work, and mobile sources are already low-noise. Head-Fi, Oct 2014
• 2015-01-14Watts agrees, adding that for best sound quality it may help to power down the source not in use. needs context Head-Fi, Jan 2015
• 2015-04-15Watts confirms isolation follows the USB chip, which draws PC power, so Hugo lacks it; laptops cause earth-loop and RF problems phones do not, and isolation removes audible laptop differences. article, Apr 2015
• 2015-07-19Watts says the USB source was his worst-sounding Dell T1650, measurements matter before listening, yet he often hears clear differences that measure identically. Head-Fi, Jul 2015
• 2016-01-03Watts says Dave is insensitive to the digital source if the data is bit perfect, though the rest of a system may still be affected by RF noise and jitter. Head-Fi, Jan 2016
• 2016-01-04Watts explains that source differences heard with Hugo came from RF noise (noise floor modulation heard as brightness) and correlated ground currents degrading depth, which Dave's galvanic isolation removes. Head-Fi, Jan 2016
• 2016-03-01Watts says Dave is source-insensitive through bit-perfect data and immunity to jitter and noise, that depth needs perfect small-signal accuracy (350 dB noise shapers), so no pre-amp sounds better. Head-Fi, Mar 2016
• 2016-05-14Watts reports DAVE via headphones sounded smoother and more natural with his laptop on battery than on mains, a small change he says is consistent with lower RF noise. Head-Fi, May 2016
• 2016-06-21Watts says DAVE's USB isolation leaves 2 pF coupling, about 79 ohms at 1 GHz, and plans a JitterBug test to find whether laptop RF arrives via mains or USB. Head-Fi, Jun 2016
• 2016-06-27Watts reports a JitterBug lifted DAVE with a mains-powered laptop from 0% to 75% but made no difference on battery, concluding RF couples mainly via USB. Head-Fi, Jun 2016
• 2016-06-27Watts plans to try a microRendu, saying reported smoothness suggests lower RF noise, though a battery source with no earth ought to inject the least RF into DAVE. Head-Fi, Jun 2016
• 2016-07-18Watts explains how source RF couples into DAVE through the USB isolator's 2 pF capacitance and ground plane, raising noise floor modulation, and why a battery-powered laptop avoids it. Head-Fi, Jul 2016
• 2016-07-18Watts says audibility depends on the DAC: unlikely with DAVE or a battery source, but an SSD may help DACs lacking USB galvanic isolation or PSU RF filtering. needs context Head-Fi, Jul 2016
• 2016-07-24Watts says fully isolating DAVE from a USB source needs the source free of earth and mains cables, so he uses portable hard disks, and wireless should be fine. Head-Fi, Jul 2016
• 2016-08-28Watts says DAVE's USB 5 V is isolated, and battery-laptop or USB-vs-optical differences are tiny; optical gives full RF isolation, USB slightly better timing from DAVE's clock. Head-Fi, Aug 2016
• 2016-09-15Watts says he uses a low-power HP Pavilion on battery and an MSI i7 laptop on the road, runs JRiver 21, and finds ASIO slightly better than WASAPI with Mojo. Head-Fi, Sep 2016
• 2017-03-04Watts says a laptop off the mains and connected only to the DAC forms no ground or power loops, so it is perfectly isolated. Head-Fi, Mar 2017
• 2017-03-05Watts cautions one laptop test proves little: Hugo 1 improved enormously with isolation from a Dell PC, while galvanic isolation on production Blu 2 with DAVE gives a substantial improvement. Head-Fi, Mar 2017
• 2017-03-16Watts explains that an earthed power amp lets source currents loop through Hugo 2's ground plane, while optical, galvanic isolation or battery sources prevent this. Head-Fi, Mar 2017
• 2017-04-07Watts says his MSI laptop tests suggest no galvanic isolation is needed on battery power, and even on mains the change is not large. Head-Fi, Apr 2017
• 2017-06-17Watts says he will be listening to a microRendu shortly. Head-Fi, Jun 2017
• 2017-10-02Watts says he hears no difference between USB cables on DAVE, optical versus USB is minute, and a battery source via DAVE's isolated USB isolates better than mains-powered optical. Head-Fi, Oct 2017
• 2017-10-31Watts agrees that a power-efficient Windows computer is the best way to go. needs context Head-Fi, Oct 2017
• 2017-12-02Watts says he heard no optical vs USB difference on Hugo 2 from his laptop with headphones, a small one with grounded outputs, and credits improved USB RF filtering. Head-Fi, Dec 2017
• 2018-01-11Watts says benefits likely depend on how noisy the source is, believing his newer, more efficient MSI laptop creates much less noise than his old Dell PC. Head-Fi, Jan 2018
• 2018-01-11Watts says the USB issue was fixed, but Poly has DLNA gap problems depending on the app; Chord is working with apps like Glider on gapless playback. Head-Fi, Jan 2018
• 2018-01-12Watts says a battery-powered laptop via USB matches optical; USB's slight brightness is RF pick-up, not better timing, and vanishes when the laptop is unplugged from mains. Head-Fi, Jan 2018
• 2018-01-16Watts says with low-noise sources USB equals optical, while noisy sources favor optical; if they sound the same, USB is preferable as it covers all files. Head-Fi, Jan 2018
• 2018-01-24Watts says RF noise from the Blu-ray player likely adds noise floor modulation, making it brighter, and whichever source sounds warmer is technically better. Head-Fi, Jan 2018
• 2018-03-08Watts says a session comparing mains, cables and servers brought disagreement but nothing technically unexplainable; all agreed his battery MSI laptop had better depth, though others preferred the custom server. Head-Fi, Mar 2018
• 2018-03-29Watts says active electronics add RF noise so sources should be simple and battery powered, Hugo 2 cuts out at 60 deg C, and thermal cycling, not warmth, harms reliability. Head-Fi, Mar 2018
• 2018-04-04Watts says he was not involved in the Poly project, but its rationale was 768 kHz operation, which only Wi-Fi allows. article, Apr 2018
• 2018-04-08Watts says his MSI laptop PSU is grounded with many ground loops; DAVE with a battery laptop sounds better, but only by careful AB listening. Head-Fi, Apr 2018
• 2018-05-04Watts says with his MSI laptop and headphones Hugo 2 sounded the same on optical and USB, a power amp reveals differences, and optical is the source benchmark. Head-Fi, May 2018
• 2018-05-17Watts says a high-end server had better tonal balance than a slightly dark battery laptop, but he hears its RF noise clearly; the laptop's depth improvement was easy to hear. Head-Fi, May 2018
• 2018-05-17Watts says servers sound brighter with an illusion of transparency, hallmarks of RF noise, mostly via RF-sensitive power amps; a laptop feeding only Dave's USB gives the lowest RF. Head-Fi, May 2018
• 2018-05-17Watts says with bit perfect USB data only RF noise can change the sound, by creating noise floor modulation that sounds brighter; jitter has no influence on his DACs. Head-Fi, May 2018
• 2018-07-06Watts suggests sound differences between CD players into Qutest via optical likely come from differing error rates, or RF upsetting the headphone amp, and says rips give error-free data. Head-Fi, Jul 2018
• 2018-07-29Watts hears no difference between battery and the supplied PSU, warns non-supplied PSUs may void warranty (never above 15V), and found laptop battery vs mains and optical vs USB identical. Head-Fi, Jul 2018
• 2018-07-29Watts uses a Poweradd Pilot Pro 2 at 12V, says batteries are not worth it for TT2, and hears no change with his mobile in airplane mode. Head-Fi, Jul 2018
• 2018-08-02Watts says Blu 2 and M scaler filter code is identical, explains that upscaling recovers transient timing rather than adding information, and why pulse array needs DSD converted to PCM. Head-Fi, Aug 2018
• 2018-08-06Watts says source results vary (YMMV); his MSI laptop's optical and USB sound the same, but that will not hold for all laptops or sources. Head-Fi, Aug 2018
• 2018-09-03Watts says certified USB cables sound the same, but one audiophile cable, servers and reclockers sounded brighter with poorer depth from RF noise; a battery bit perfect source is ideal. Head-Fi, Sep 2018
• 2018-11-02Watts says a bit-perfect optical source always sounds and measures the same, in his experience, on Hugo 2 or any other Chord DAC. Head-Fi, Nov 2018
• 2018-11-06Watts says servers bring no sound-quality gain, their perceived transparency being RF noise raising noise floor modulation and brightness, while the M scaler transforms musical performance. Head-Fi, Nov 2018
• 2019-02-09Watts says a cyan input light shows M Scaler dual data and 1M taps; optical matching USB proves his DPLL removes source jitter, and simpler, lower-power sources sound better. Head-Fi, Feb 2019
• 2019-02-22Watts says TT2 and M Scaler USB inputs are galvanically isolated, drawing about 250 mW from the source, which may drain a phone about 15% faster. Head-Fi, Feb 2019
• 2019-03-16Watts says USB VBUS powers the decoder on the isolator's source side, so only ground loops let sources matter, and added source complexity can sound like improvement while degrading timbre. Head-Fi, Mar 2019
• 2020-01-18Watts explains how a mains-powered USB-to-optical converter can create RF ground-current loops a DAC may intersect, advises keeping sources simple, and notes Ethernet isolation still has capacitive coupling. Head-Fi, Jan 2020
• 2020-01-20Watts says source-related SQ changes are now small, that low-power laptops and especially his phone are the best sources, and that he will retest sources against optical. Head-Fi, Jan 2020
• 2020-05-05Watts says data integrity plays no part, as long M scaler tests at -200dB never showed a bit error, but injected noise and processor activity can change the sound. Head-Fi, May 2020
• 2020-08-11Watts calls amps that short inputs reckless, and says his MSI laptop beat a server, which sounded bright with false transparency from RF-induced noise floor modulation. Head-Fi, Aug 2020
• 2020-08-11Watts advises waiting for Dave, then comparing a desktop PC with an ungrounded battery laptop; if they sound the same, the source need not be a concern. Head-Fi, Aug 2020
• 2020-08-13Watts says the best source injects least RF noise into the DAC ground; a battery phone is lowest noise; the USB decoder sits on the isolation's source side. Head-Fi, Aug 2020
• 2020-09-02Watts says Poly was not his project and quotes Chord's Matt Bartlett explaining it was designed from scratch as a low-power battery streamer, which is why it costs more. Head-Fi, Sep 2020
• 2020-09-20Watts says a phone playing bit-perfect local files is the best source, being low-power and battery-run, advises matching a streamer to it, and had no part in 2go or 2yu. Head-Fi, Sep 2020
• 2020-10-10Watts sees no point in USB clocks since TT2's isolation follows the USB decoder, says added source devices raise RF noise, and lists laptops and a phone as his sources. Head-Fi, Oct 2020
• 2021-03-07Watts keeps music locally, says jitter is not a problem for his DACs but RF is, so keep sources simple, as extra boxes add RF heard as false brightness. Head-Fi, Mar 2021
• 2021-03-19Watts says optical cannot pass source ground-plane noise, mains ground loops are mostly theoretical, and suggests a phone with a bit-perfect app as a reference source. Head-Fi, Mar 2021
• 2021-03-22Watts attributes differences between CD players into Dave over optical to mains RF noise and ground loops, and says bit-perfect source differences come from jitter, RF noise or signal-correlated noise. Head-Fi, Mar 2021
• 2021-04-07Watts says USB can equal optical, as with his old MSI laptop, but on his new desktop PC optical sounded clearly better; with noisier sources optical wins. Head-Fi, Apr 2021
• 2021-11-08Watts says he will not design streamers, since a perfect DAC should sound the same with any bit-perfect source, though Chord might someday combine a streamer with a scaler. Head-Fi, Nov 2021
• 2022-02-21Watts says putting the source and M scaler on one battery keeps source RF from the DAC; the M scaler's USB isolation exists only to cut noise reaching the DAC. Head-Fi, Feb 2022
• 2022-02-22Watts says optical versus USB depends on the source, identical on his laptop but optical better on his design PC; battery sources off mains make no difference. Head-Fi, Feb 2022
• 2022-03-19Watts says Mojo and Hugo 2 lack galvanic isolation and that galvanic isolation in general is about 99% effective; optical helps with noisy servers, and his MSI desktop sounds much better on optical. MFG Audio Reviews 56:58
• 2022-06-19Watts says he would never design a power bank; his focus is making his designs immune to attached sources and supplies, which he admits needs more work. Head-Fi, Jun 2022
• 2022-12-13Watts says audiophile USB cables add RF or sound identical, optical (KableDirekt) is best, a phone or battery laptop is the reference source, and Wave Stream cables help. Head-Fi, Dec 2022
• 2023-02-04Watts says he was asked yesterday why there is no Chord streamer, and that he chooses projects he wants to do, to enjoy music more, not to make money. Dusty Audio 48:07
• 2023-02-04Watts says with bit-perfect data any source should sound identical, but with his current DACs they do not, and he is improving the DAC to be source-independent. Dusty Audio 48:52
• 2023-02-04Watts says making the DAC insensitive to streamer noise is a better use of his time than streamers, and Chord will likely hire others to develop streamers for his DACs. Dusty Audio 49:41
• 2023-02-04Watts says the streamer must be separate from the DAC because processing noise, even nanovolts of RF, degrades performance, and separation helps contain it. Dusty Audio 51:22
• 2023-02-04Watts says on planes, about 300 hours a year, he uses his phone with 1 TB of music by USB into a battery DAC, giving perfect isolation. Dusty Audio 1:06:27
• 2023-02-04Watts says with his MSI laptop into the M Scaler and Dave, optical and USB sounded the same so he used USB, before his son built him a high-performance computer. Dusty Audio 1:07:10
• 2023-02-04Watts says his 800 W desktop's USB sounded significantly worse than optical into the M Scaler; optical is the reference because no current flows into the DAC. Dusty Audio 1:07:51
• 2023-02-04Watts says the source does not really matter, but use optical as the reference to judge it. Dusty Audio 1:08:42
• 2023-02-05Watts says he uses his mobile phone as the source, with one terabyte of storage. Soundnews 1:26
• 2023-02-05Watts says streamers are not something he spends a lot of time on. Soundnews 10:03
• 2023-02-05Watts says with bit-perfect data, streamers sound different only because of the DAC's sensitivity; a perfect DAC would make all sources sound the same, so a streamer would not help. Soundnews 10:21
• 2023-02-05Watts says his focus is making the DAC much more tolerant, so a poor source and a very high quality source sound the same. Soundnews 11:09
• 2023-10-01Watts says Chord listens with many headphones and, more importantly, many USB and other sources to find any gotchas. The Source AV 40:08
• 2024-01-07Watts says 16FS is the interpolation sweet spot (1.3uS vs 2.6uS timing at 8FS for 48kHz), adding more 200T FPGAs is the economic path, and a battery laptop via optical is hard to beat. Head-Fi, Jan 2024
• 2024-02-29Watts says optical is the reference input for Mojo 2, while USB from a quiet or battery-powered source such as a phone sounds identical, given bit-perfect data. Head-Fi, Feb 2024
• 2024-03-20Watts introduces his new seminar 'Digital Isn't' and the myth that digital cables and sources cannot change sound because the data is bit perfect; he says they can. MFG Audio Reviews 0
• 2024-03-20Watts previews his points: linear power supplies create distortion, passive components can measure perfectly yet change sound, and cables and sources can differ despite bit-perfect data. MFG Audio Reviews 1:32
• 2024-03-20Watts names three ways a source can change a DAC's sound (jitter, random RF noise causing noise floor modulation, correlated RF noise) and defines jitter as clock-timing uncertainty. MFG Audio Reviews 2:33
• 2024-03-20Watts explains two's complement coding: near zero, a slightly negative signal flips all bits to ones, as a processor moves music data from memory to the USB output. MFG Audio Reviews 19:32
• 2024-03-20Watts says processor state changes create GHz noise bursts correlated with the signal and worst for small signals; the DAC's analog circuitry demodulates this into audio-band noise corrupting small signals. MFG Audio Reviews 20:22
• 2024-03-20Watts says a low-power processor reduces correlated RF noise, so a mobile phone can be the best source: battery operation stops current flow and low power means little GHz noise. MFG Audio Reviews 22:11
• 2024-03-20Watts says a low-power battery source removes both correlated and random RF noise, giving better depth and a warmer sound, and that optical, reputedly worst, is best because coupling capacitance is zero. MFG Audio Reviews 22:54
• 2024-03-20Watts says optical should be the reference connection; USB can sound identical with a low-power battery source, and on an old MSI laptop USB and optical sounded the same. MFG Audio Reviews 24:40
• 2024-03-20Watts says his powerful MSI design computer shows substantial differences between optical and BNC, and in his tests high-end USB cables tend to sound brighter by increasing RF noise. MFG Audio Reviews 25:32
• 2024-07-12Watts says he developed a supply with special RF filters giving battery-like isolation, reducing sensitivity to BNC cables and sources, and raises why he does not build a network player. HIFICLUB 46:35
• 2024-07-12Watts says with a perfect M Scaler and DAC every bit-perfect source would sound the same, so he hardens DACs and scalers against source noise, focusing on the power supply. HIFICLUB 47:23
• 2025-02-17Watts answers yes, network gear does affect sound, and says he always uses material stored on his SSD. needs context audio-2G 11:52
• 2025-02-17Watts says streams can be different recordings (two Norah Jones versions differ greatly), and he designs no source because a perfect DAC fed bit-perfect data would make the source irrelevant. audio-2G 12:43
• 2025-02-17Watts says a perfect DAC fed bit-perfect data would make no difference to sound quality, so he focuses on making the DAC tolerant of RF noise, jitter and other influences rather than on sources. audio-2G 13:29
• 2026-05-03Watts says he is not working on a streamer; his aim is for DACs to sound the same with poor and good streamers, so long as the data is bit perfect. Audio Force 18:19