Can I make an XLR-to-RCA adaptor by shorting the negative pin?

Practical answer. Do not connect pin 3 to ground Head-Fi, May 2021Head-Fi, Apr 2022. To feed an RCA input from the XLR output, Watts says to use a cable that uses only pin 1 (ground) and pin 2 (positive or signal) Head-Fi, Jan 2021Head-Fi, May 2021Head-Fi, Apr 2022. For TT2 he added in 2023 that if the amp's XLR input shorts the negative to ground, you should "Stick to RCA in that case, as you can damage TT2." Head-Fi, Jan 2023. All sources are Head-Fi posts; several TT2-thread dates are estimated.

Hugo TT2

• Pin layout. In April 2022 he gave TT2's standard as "1 is gnd, 2 positive in phase and 3 negative out of phase" Head-Fi, Apr 2022. In 2021 he said pin 2 equals the RCA phono signal, the negative comes from an inverting amplifier, and the XLR outputs are wired directly to high output current stages Head-Fi, Jan 2021Head-Fi, Mar 2021.
• The warning, by date. July 2020: some subs short pins 1 and 3, and "this will cause problems, as you will short the negative outputs" Head-Fi, Jul 2020. January 2021: some amplifier XLR inputs short pins 1 and 3, which "can cause damage to TT2, so take care that XLR inputs are truly balanced" Head-Fi, Jan 2021. March 2021: the same problem "could cause damage to TT2" Head-Fi, Mar 2021. April 2022: "Always check that when using XLRs that pin 3 is not connected to pin 1 as this will short the negative output which may damage TT2." Head-Fi, Apr 2022. January 2023: shorting the "high power low impedance negative TT2 output" can damage TT2 Head-Fi, Jan 2023. June 2024: "A short can damage TT2, and very large currents will flow" Head-Fi, Jun 2024.
• Single-ended wiring. In January 2019 he said he drives his own speakers from TT2's XLR in single-ended mode, "pin 1 (gnd) and pin 2 (hot)" Head-Fi, Jan 2019, and he recommended pins 1 and 2 for speakers again in 2020 and 2022 Head-Fi, Jul 2020Head-Fi, Apr 2022. In the TT2 thread in April 2022: "No problem to use the XLRs - just use pin 1 (ground) and pin 2 (hot)." Head-Fi, Apr 2022. Single-ended XLR alongside the RCA into a high-impedance input is fine (March 2021) Head-Fi, Mar 2021.
• In April 2019 he said TT2's XLR pin 1 must connect to pin 1 on the amp, otherwise large common-mode differences "may damage the electronics for the amp" Head-Fi, Apr 2019.

Dave

• On 23 January 2021 in the Dave thread: "So for XLR to single ended use pin 1 for gnd, pin 2 for pos or signal." Head-Fi, Jan 2021. The next day he replied: "No never do that with electronic balanced outputs - you will short the negative output amplifier. That could damage the DAC and will certainly degrade sound quality." Head-Fi, Jan 2021. The question is not archived, and the reply does not name Dave.
• In 2021 he said Dave's XLR is pin 2 positive and pin 3 negative Head-Fi, Apr 2021, that Dave's XLR outputs go through 33 ohm resistors, and that Dave's negative output is not high current and was intended to drive amplifiers only Head-Fi, Mar 2021.
• In February 2016 he said "production Dave now has short circuit protection resistors installed on the balanced XLR" Head-Fi, Feb 2016. In August 2020, about amps that short their inputs, he said "With Dave driving a short it will get distorted." Head-Fi, Aug 2020. He did not say how the protection resistors relate to the damage risk he named in 2021.

Posts that name no product

• November 2018: "For SE use pin 1 and pin 2." Head-Fi, Nov 2018. March 2021: "If it's connecting to a power amp then you need pin 1 ground connected." Head-Fi, Mar 2021. May 2021: "Ouch! Can't connect 1 and 3 to ground, as that will short the negative output." Head-Fi, May 2021.
• July 2022: running XLR and RCA together is fine, but "make sure the XLR input of the sub or amp does not short pins 1 and 3 together - that advice applies whenever you use the XLRs" Head-Fi, Jul 2022; three days later he repeated the caution for a sub Head-Fi, Jul 2022.

A post that reads differently

In April 2022 in the Dave thread he wrote that if the RCA input is grounded, its ground goes to XLR pin 1, and "If it's a balanced input, connect XLR pins 1 and 3 to the RCA ground, and XLR pin 2 to the signal pin" Head-Fi, Apr 2022. The question is not archived, and he says the answer "depends upon how the XLR is wired on the amp", so it is not clear the XLR in question is a Chord output.

What he has not said. This archive has no statement from Watts about ready-made XLR-to-RCA adaptors, and none about this wiring on Chord models other than TT2 and Dave. Beyond possible damage, degraded or distorted sound, and large currents creating noise, he did not describe what a short does Head-Fi, Jan 2021Head-Fi, Aug 2020Head-Fi, Jun 2024. No transcript or article passage addresses the question.

Quotes

“No never do that with electronic balanced outputs - you will short the negative output amplifier.”2021-01-24 Head-Fi, Jan 2021

“You need need a cable that just uses pins 1 (gnd) and 2 (pos OP) for connecting to a phono.”2021-05-25 Head-Fi, May 2021

“Always check that when using XLRs that pin 3 is not connected to pin 1 as this will short the negative output which may damage TT2.”2022-04-12 Head-Fi, Apr 2022

“No problem to use the XLRs - just use pin 1 (ground) and pin 2 (hot).”2022-04-11 Head-Fi, Apr 2022

“Stick to RCA in that case, as you can damage TT2.”2023-01-11 Head-Fi, Jan 2023

Dated positions

Caveats and open points

• All statements come from Head-Fi forum posts; several TT2-thread dates are estimated from post IDs.
• Head-Fi, Jan 2021 is archived without the question it answers and names 'electronic balanced outputs', not Dave.
• Head-Fi, Apr 2022 is archived without its question; it may concern an amplifier's XLR input rather than a Chord XLR output.
• Head-Fi, May 2021, Head-Fi, Jul 2022 and Head-Fi, Jul 2022 (Watts Up thread) name no product.
• Nothing in this archive covers ready-made adaptors or Chord models other than TT2 and Dave for this wiring.
• No transcript or article passage addresses this question.

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