Balanced vs single-ended

Analog stage, outputs and amplification

Answers on this topic

• Can I make an XLR-to-RCA adaptor by shorting the negative pin?
• Should I use balanced or single-ended headphone drive, and why are Chord headphone outputs single-ended?
• Should I use the RCA or XLR line outputs on TT2 or DAVE into my amplifier?

Everything he said on this topic (87)

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

• 2014-08-20Watts explains chip DACs are differential for substrate and reference noise reasons, while Hugo is fully single-ended with one output stage, so balanced adds complexity. Head-Fi, Aug 2014
• 2015-02-02Watts says Hugo TT's balanced output is for driving balanced power amps directly and declines to discuss balanced headphone drive. Head-Fi, Feb 2015
• 2015-02-02Watts describes TT's floating balanced output, says TT uses batteries for mains isolation though 2Qute proved RF filtering matches it, and lists balanced drive's pros and cons. Head-Fi, Feb 2015
• 2015-06-29Watts says the balanced output is +6dB over the single-ended output. needs context Head-Fi, Jun 2015
• 2015-06-30Watts says Dave's wide output level and low noise make power amp gain unimportant, and Dave is single-ended because that is best for sound, though harder than differential. Head-Fi, Jun 2015
• 2015-07-14Watts says balanced doubles signal-path components and costs transparency; silicon DACs need differential operation, but his discrete DACs are single-ended, which forced solving problems differential hides. Head-Fi, Jul 2015
• 2015-07-19Watts explains why balanced amplifiers suffer common-mode non-linearity and RF decoupling problems, says balanced mode flattened depth on his amp, but suggests trying balanced if SE is noisy. Head-Fi, Jul 2015
• 2015-08-01Watts says Dave, like Hugo, uses the same output for headphones and line level; XLR gives up to 12v RMS but is not for headphones; RCA gives 6v RMS. Head-Fi, Aug 2015
• 2015-12-01Watts says do not drive headphones from Dave's balanced outputs; Dave drives the HE1000 easily at 1.4W into 33 ohms, and an external amp would add distortion. Head-Fi, Dec 2015
• 2015-12-02Watts says Dave runs warm with large thermal margins, XLR headphone drive would distort, AES is poor for high rates, and Blu dual BNC works with proper RF cables. Head-Fi, Dec 2015
• 2016-02-19Watts says production Dave has short-circuit protection resistors on the balanced XLR, so it will not drive headphones, and he prefers crossfeed setting 3 as closer to loudspeakers. Head-Fi, Feb 2016
• 2016-03-17Watts says the balanced output is not for driving headphones because its current is too low and impedance too high. Head-Fi, Mar 2016
• 2017-02-05Watts says Dave driving valve power amps directly has always sounded superb and more transparent without a pre-amp, and suggests the 33 ohm balanced outputs if an amp goes unstable. Head-Fi, Feb 2017
• 2017-02-06Watts says his amp is not Class D, since even 1.6 MHz switching causes timing errors, but linear Class A with one global feedback path; RCA is usually best. Head-Fi, Feb 2017
• 2017-10-24Watts suggests using DAVE's balanced output and its volume control to avoid driving the ADAM speakers with too high a voltage. Head-Fi, Oct 2017
• 2018-02-19Watts explains his discrete single-ended DAC combines I-to-V, filtering and headphone drive in one amplifier with two resistors and two capacitors; DAVE's balanced outputs add an inverting amplifier. Head-Fi, Feb 2018
• 2018-04-04Watts says there are no plans for balanced designs: doubling signal-path parts degrades depth and detail, single-ended drives power-hungry headphones, and balanced is needed only for some loudspeakers. article, Apr 2018
• 2018-05-16Watts says TT2's balanced negative output uses the same amplifier as its single-ended output, so the balanced output is low distortion and simple, unlike Dave's. Head-Fi, May 2018
• 2018-05-19Watts says balanced drive gives headphones no benefit, so use TT2's XLR only for voltage or power needs, balanced power amps or loudspeakers; HD800S are easy to drive. Head-Fi, May 2018
• 2018-05-22Watts says Dave's negative output uses an op-amp for power amps only, while TT2's uses its high-power discrete stage for speakers and headphones, and suggests XLR-terminated headphone cables. Head-Fi, May 2018
• 2018-05-24Watts says TT2 would reach 103 dB on a 91 dB speaker, the balanced output has double the impedance, and SE would give 114 dB with an LCD-4. Head-Fi, May 2018
• 2018-06-23Watts says the linked XLR adaptors look fine for an HD800 on TT2 but adaptors noticeably degrade sound long term, and notes TT2's XLR outputs are male. Head-Fi, Jun 2018
• 2018-07-15Watts confirms TT2's SE outputs are simplest and potentially most transparent, with balanced needed only for extra power, though some power amps and cables prefer XLR. Head-Fi, Jul 2018
• 2018-08-05Watts says TT2's SE output gives the Abyss 2W or 121 dB SPL, the balanced 8W or 127 dB, and the balanced path's extra parts slightly reduce transparency. Head-Fi, Aug 2018
• 2018-10-03Watts explains TT2's single-stage SE output amplifier, the relay-switched resistor that sets low gain, and the inverted stage that creates the balanced negative output. Head-Fi, Oct 2018
• 2018-11-11Watts says his adaptors allow balanced (18W/8) or single-ended (7W/8 ohms) speaker drive, with the green terminal as ground. needs context Head-Fi, Nov 2018
• 2018-11-11Watts says TT2 can drive B&W loads dipping to 3 ohms thanks to supercap reserves and a 10A current limit, and suggests trying 7W SE before balanced. Head-Fi, Nov 2018
• 2018-11-20Watts says the setup should be OK, as the SE amp will see currents from the sub and full-range speakers, fine if both are 8 ohms; XLR gives +6 dB more output. needs context Head-Fi, Nov 2018
• 2018-11-20Watts gives the XLR wiring: pin 2 positive, pin 3 negative, pin 1 ground; for single-ended use pins 1 and 2. Head-Fi, Nov 2018
• 2019-01-16Asked whether TT2's RCA and XLR outputs can be used together in amp mode, for a sub and an amp, Watts says yes. Head-Fi, Jan 2019
• 2019-01-21Watts drives B&W 803D3 from TT2 single-ended via XLR pins 1 and 2, explains the third-order filter to 2048FS, and uses green for his 96k recordings. Head-Fi, Jan 2019
• 2019-01-31Watts says TT2 supercaps last over 11 years, it can stay on, warm-up takes about 10 minutes, pre-amps cost transparency, and linear PSUs at best sound the same. Head-Fi, Jan 2019
• 2019-02-05Watts says balanced adds complexity that affects transparency, but its benefit depends on cables, length and gear, so he advises trying both. Head-Fi, Feb 2019
• 2019-03-12Watts says to consider TT2's balanced output only at +6H or above, and its low gain setting is about 6 dB quieter than Mojo. Head-Fi, Mar 2019
• 2019-04-11Watts says TT2's balanced output gives double the voltage, so -3H is 6 V and +6H is 16.92 V RMS balanced. Head-Fi, Apr 2019
• 2019-04-14Watts says whether balanced or RCA is better into active speakers depends on the equipment, and advises trying both. Head-Fi, Apr 2019
• 2019-04-21Watts says pin 1 of TT2's XLR must connect to pin 1 on the amp, or large common-mode differences could damage the amp. Head-Fi, Apr 2019
• 2019-07-03Watts says TT2's negative output uses the same output stage design as the positive or SE outputs, so the 5 A peak applies to both. Head-Fi, Jul 2019
• 2019-10-24Watts calls converting to balanced a crazy idea that only adds complexity, since a headphone sees the same voltage across a load either way. Head-Fi, Oct 2019
• 2020-01-06Watts says the Dubai events are public; his DACs are innately single-ended so balanced adds circuitry, while chip DACs must be balanced to reject substrate noise. Head-Fi, Jan 2020
• 2020-07-07Watts says TT2's real PSU is internal (inductor, supercaps, RF filters), recommends XLR pins 1 and 2 for speakers, and warns some subs short pins 1 and 3. Head-Fi, Jul 2020
• 2020-07-29Watts advises staying single-ended for the Abyss TC on TT2; -20H is low, up to +6H is possible, but that would reach a hearing-damaging 121dB SPL. Head-Fi, Jul 2020
• 2020-08-16Watts says analog cables matter so he makes his own, and active balanced headphone outputs degrade transparency with no benefit given TT2's 9.3 V RMS and 5 A single-ended drive. Head-Fi, Aug 2020
• 2020-11-23Watts says TT2's balanced output into 4 ohms may thermally trip, restarting once cool, single-ended into 4 ohms won't trip, and Dave would have no problem with the Voxativ. Head-Fi, Nov 2020
• 2021-01-08Watts says TT2 drives efficient speakers single-ended, but XLRs thermally trip into 8 ohms or less; 16 ohms is fine, and amps shorting pins 1 and 3 risk damage. Head-Fi, Jan 2021
• 2021-01-08Watts says active ATC speakers on TT2's XLRs are fine if the input is truly balanced, as pro gear will not short balanced outputs. Head-Fi, Jan 2021
• 2021-01-09Watts confirms the XLR wiring and says TT2 XLR gives the Abyss 7W per channel (126 dB SPL) and single-ended 1.8W (120 dB), so stay single-ended. Head-Fi, Jan 2021
• 2021-01-20Watts says balanced adds amplifiers that cost transparency, so his DACs are single-ended; halving gain halves noise for IEMs; linear PSUs add RF and noise floor modulation. Head-Fi, Jan 2021
• 2021-01-20Watts says balanced always costs a little transparency from an extra stage; headphones see only the voltage difference, while with power amps balanced can sometimes sound better. Head-Fi, Jan 2021
• 2021-01-20Watts says XLR pin 2 equals the RCA signal, the outputs handle over 5A RMS, single-ended drives the Abyss 1266 to 120dB, and balanced comparisons must be volume matched. Head-Fi, Jan 2021
• 2021-01-23Watts says that for XLR to single ended use pin 1 for ground and pin 2 for positive or signal. Head-Fi, Jan 2021
• 2021-01-24Watts warns never to do that with electronic balanced outputs, as it shorts the negative output amplifier, which could damage the DAC and degrades sound quality. needs context Head-Fi, Jan 2021
• 2021-03-25Watts says TT2's XLR used single-ended into a high-impedance input is fine, but some XLR inputs short pins 1 and 3; avoid balanced loads at or below 10 ohms. Head-Fi, Mar 2021
• 2021-03-26Watts says TT2's XLR outputs connect directly to high-current output stages, while Dave's go through 33 ohm resistors with a low-current negative leg, meant for amplifiers, not headphones. Head-Fi, Mar 2021
• 2021-03-27Watts says the wiring is fine for headphones, but a connection to a power amp needs pin 1 ground connected. needs context Head-Fi, Mar 2021
• 2021-04-21Watts says Dave's XLR is pin 2 positive and pin 3 negative, so set Dave to negative phase if the power amp does not also invert. Head-Fi, Apr 2021
• 2021-04-30Watts says balanced XLR doubles the voltage into a power amp, a +6dB change, and Dave's XLR outputs are for pre or power amps only, not headphones. Head-Fi, Apr 2021
• 2021-05-25Watts warns that connecting XLR pins 1 and 3 to ground shorts the negative output, and says a phono cable should use only pins 1 and 2. Head-Fi, May 2021
• 2022-01-31Watts says Mojo 2's UHD DSP is his own core, balanced outputs would degrade transparency, a USB-C charging port would not fit, and musicality comes first. Head-Fi, Jan 2022
• 2022-02-17Watts says TT2 should not use balanced outputs into speakers or loads under 16 ohms as it will thermally trip; single-ended drives his B&W 803 D3 loud enough. Head-Fi, Feb 2022
• 2022-03-27Watts says he would run Susvara from TT2 single-ended (95dB SPL; XLR gives 101 dB), warns over 80dB long-term damages hearing, and would never add a headphone amp. Head-Fi, Mar 2022
• 2022-04-11Watts says the XLRs can be used single-ended with pin 1 as ground and pin 2 as hot. Head-Fi, Apr 2022
• 2022-04-12Watts gives the XLR pin standard, says speakers should use the single-ended connection, and warns that pin 3 shorted to pin 1, as some amp inputs do, may damage TT2. Head-Fi, Apr 2022
• 2022-04-12Watts says TT2 will thermally shut down driving 8 ohm loads or less in balanced mode, and anyone not seeing shutdowns does not need the extra power. Head-Fi, Apr 2022
• 2022-04-19Watts explains wiring an RCA output into an amp's XLR input for grounded versus balanced inputs, then describes SPICE modeling of active parts, passive parts and PCB tracks. Head-Fi, Apr 2022
• 2022-05-07Watts prefers optical over coax, uses regular optical cables plus a 2m Lifatec optical cable for 192k and Wave Stream BNC cables on the M scaler, and sees no benefit in I2S or balanced. Head-Fi, May 2022
• 2022-07-02Watts clarifies he meant not to drive speakers from TT2's balanced XLR output; using XLR pins 1 and 2 to drive speakers is fine. Head-Fi, Jul 2022
• 2022-07-16Watts says running the XLR and RCA outputs at the same time is fine, provided the sub or amp's XLR input does not short pins 1 and 3. Head-Fi, Jul 2022
• 2022-07-19Watts says feeding a sub from the XLR or RCA output makes no difference, assuming the sub accepts balanced input without shorting pins 1 and 3. Head-Fi, Jul 2022
• 2022-07-19Watts says TT2 has no line output: single-ended is volume-adjusted from 0 to 9V RMS and XLR doubles that to 18V, so a sub can be fed from either. Head-Fi, Jul 2022
• 2022-08-26Watts explains TT2's balanced output (gain 5 and -1 amps), says single-ended is more transparent owing to fewer feedback parts, shows measurements, and says the pulse array is his IP. Head-Fi, Aug 2022
• 2023-01-11Watts says the fault lies with the amp, whose XLR input shorts the negative leg to ground; he advises using RCA instead, since the short can damage TT2. Head-Fi, Jan 2023
• 2023-03-28Watts says his signal path has two resistors and two capacitors thanks to low noise at 1 MHz, and is single-ended with one amplifier driving headphones, unlike differential DACs. The Headphone Show 49:35
• 2023-03-30Watts gives Stealth SPL at 0dBFS (98.3 dB Hugo/Mojo, 100.0 Dave, 103.4 TT2 headphone, 109.1 balanced), warns against long listening above 80dB, and suggests volume settings. Head-Fi, Mar 2023
• 2023-03-31Watts says balanced outputs add an amp stage and slight transparency loss but reject common-mode noise; RCA suits short runs, XLR perhaps long ones, with 6dB more gain. Head-Fi, Mar 2023
• 2023-04-01Watts says the case where he heard balanced was much better involved cables longer than 5m. Head-Fi, Apr 2023
• 2023-06-21Watts breaks down background noise sources and Mojo 2's trade-offs (2.2 nV/rtHz, 5.2 V RMS), warns attenuators harm sound, and cites 4.4 mm connector cost. Head-Fi, Jun 2023
• 2023-10-01Watts says you do not need balanced. The Source AV 38:55
• 2023-10-01Watts says Chord could not afford to put a Pentaconn connector on the Mojo. The Source AV 38:59
• 2024-06-30Watts says faint music heard from TT2 with XLR cables suggests an amp input shorting pins 1 and 3; the large currents probably make a PSU inductor noisy. Head-Fi, Jun 2024
• 2024-10-03Watts says PCB ground layers screen EMC, the new coefficient work needs a whole 200T FPGA and won't reach the Hugo M Scaler, and single-ended has the transparency edge. Head-Fi, Oct 2024
• 2024-10-25Watts says balanced DACs still use ground-referenced I to V converters, balanced complexity raises noise floor modulation, and common mode rejection fails at RF. Head-Fi, Oct 2024
• 2025-03-27Watts says TT2's balanced outputs should not drive 8 ohm speakers, as above 7W it thermally trips; balanced is for low-sensitivity 32 ohm headphones or balanced amp inputs. Head-Fi, Mar 2025
• 2026-10-02Watts says balanced has benefits and disadvantages; DAVE has both balanced and single-ended outputs, and sometimes one is better, sometimes the other. HiFi Buys 1:08:15
• 2026-10-02Watts says balanced rejects common-mode noise and hum, mainly helpful with long cables or poor power amps, but doubles the circuitry, costing transparency, while making the output stage symmetric. HiFi Buys 1:08:33
• 2026-10-02Watts says balanced cancels second harmonics, but his very linear output stages have none, so balanced gives only losses; headphones cannot tell balanced from single-ended. HiFi Buys 1:09:22
• 2026-10-02Watts says single-ended gives better transparency if common-mode noise and output-stage distortion are low, but DAC topology matters more: a DAC modulates a reference voltage. HiFi Buys 1:10:07