Which output level should I feed my amp: Qutest's 1, 2 or 3 V setting, TT2's DAC mode or gain, or the volume control?

The practical answer

Watts says the best output level depends on the amp or pre-amp you are feeding, so he gives no single setting Head-Fi, Jul 2018Head-Fi, Mar 2023. On Qutest, his advice is to try the levels and listen, and if you are unsure, to set 2V Head-Fi, Apr 2018Head-Fi, Jan 2019. On TT2, the volume display reads absolute output, so -3 means 3V RMS with a full-scale input in either gain mode Head-Fi, Dec 2018Head-Fi, Apr 2019.

Qutest: the 1V, 2V and 3V settings

To choose a level, press the two buttons together while Qutest starts up (rainbow display); it then stays at that level Head-Fi, Jan 2018. The manual's colors are 1V red, 2V green, 3V blue (November 2019) Head-Fi, Nov 2019. In December 2018 he put 2V at 3.5 dB and 1V at 9.5 dB below 3V Head-Fi, Dec 2018.

The change is digital, with no analog changes, and noise stays at the same absolute level in all three settings (July 2018, September 2023) Head-Fi, Jul 2018Head-Fi, Sep 2023. In January 2019 he said Qutest is innately capable of much more than 3V, so there is no significant difference in internal operation or distortion, and audible differences come from the connected gear Head-Fi, Jan 2019; in February 2020 he said the same of 2V against 3V Head-Fi, Feb 2020. In September 2023 he added that 2V and 1V carry a bit more attenuation than 3V Head-Fi, Sep 2023.

The settings exist for the amp. In March 2023 he said some amps are easily overloaded at 3V, "meaning it's not clipping, but the distortion is higher and so it sounds harder" Head-Fi, Mar 2023, and in January 2024 that he had found 3V too high for some pre-amps, hence Qutest's three options Head-Fi, Jan 2024. In January 2018 he said that if an amp is rated at 1.2V, the 1V setting should sound best Head-Fi, Jan 2018. His method: "best advice is to try different levels and listen to which one is best sounding - and if you can't hear a difference then don't worry!" Head-Fi, Apr 2018.

Hugo TT2: DAC mode, gain and volume

In May 2018 he listed the options: DAC mode (fixed 2.5V RCA, 5V RMS XLR, volume disabled), low gain, or the volume control, where -3dB gives 3V RMS Head-Fi, May 2018. In February 2020 he first said amp mode at -3L is identical to DAC mode, then corrected himself: he had tweaked DAC mode down to 2.5V, the knee point of the low-gain distortion curve, and "3v can be a little too hot for a lot of pre-amps" Head-Fi, Feb 2020Head-Fi, Feb 2020. In October 2019 and July 2020 he said DAC mode equals amp mode in low gain at -5L, which he gave as 2.4V RMS Head-Fi, Oct 2019Head-Fi, Jul 2020Head-Fi, Jul 2020.

On the display, -3L and -3H give the same 3V RMS, and he said to match the displayed number when comparing gain modes Head-Fi, Apr 2019Head-Fi, Feb 2020. In June 2020 he said four clicks down from -3 is 1.89V RMS in either gain, and "If an M scaler is used, you need to set it to -4 as the M scaler attenuates by 2.75 dB" Head-Fi, Jun 2020.

With a full-scale input, low gain clips above -3L (at -2L) and high gain clips at +7H (October 2018, April 2019) Head-Fi, Oct 2018Head-Fi, Apr 2019. His figure for the low-gain maximum varies: 2.5V in June 2018 and January 2019, just over 3V in April 2019, and 3.3V in October 2019 Head-Fi, Jun 2018Head-Fi, Jan 2019Head-Fi, Apr 2019Head-Fi, Oct 2019.

His gain advice for a power amp differs by date. In May 2018 he said amp mode covers TT2 as a power amp to efficient speakers or as a digital pre-amp, and "You would just set it in low gain mode" Head-Fi, May 2018. In June 2018 he said low gain suits power amps that can't tolerate high gain's 9V RMS Head-Fi, Jun 2018, and in March 2019 he guessed low gain "would be the most appropriate setting" for driving power amps direct Head-Fi, Mar 2019. In April 2022 he said "High gain would be best when connecting a power amp" and that TT2 should be used in high gain unless sensitive IEMs hiss Head-Fi, Apr 2022Head-Fi, Apr 2022.

Pre-amps

In May 2018, writing in the DAVE thread about his DACs generally, he said that with the digital volume control "you simply do not need a pre-amp" Head-Fi, May 2018. In January 2019, in the TT2 thread, he said you will always degrade transparency by adding a pre-amp, though vinyl users need one Head-Fi, Jan 2019. For Qutest, which has no volume control, he said in March 2020 that "you would be better off using Roon to do the volume control than using a pre-amp or a passive volume control" Head-Fi, Mar 2020, and in May 2022 that Qutest "is intended to work with an analogue pre-amp or integrated amp" Head-Fi, May 2022.

What he has not said

He named no best setting for any specific amp model, and said he had no experience of one pre-amp an owner asked about Head-Fi, Apr 2018.

Quotes

“best advice is to try different levels and listen to which one is best sounding - and if you can't hear a difference then don't worry!”2018-04-19 Head-Fi, Apr 2018

“If you are unsure, then just set it to 2v, the regular CD/DAC output voltage.”2019-01-20 Head-Fi, Jan 2019

“Some amps are easily overloaded with 3v output - overloaded meaning it's not clipping, but the distortion is higher and so it sounds harder.”2023-03-12 Head-Fi, Mar 2023

“I found that the 3v was too high a level for some pre-amps - hence why Qutest had 1v, 2v and 3v fixed OP options.”2024-01-14 Head-Fi, Jan 2024

“-3dB low or high gain will give you 3v RMS in ultra low distortion all the time, guaranteed.”2019-10-10 Head-Fi, Oct 2019

“High gain would be best when connecting a power amp.”2022-04-26 Head-Fi, Apr 2022

Dated positions

Caveats and open points

• Many TT2 forum post dates are estimated from post IDs; the cited dates are approximate.
• Several TT2 statements were made in the Hugo M Scaler and DAVE threads; the DAVE-thread pre-amp statement concerns his DACs generally.
• His TT2 figures vary across posts: DAC mode 2.5V RCA (2018, 2020) or -5L at 2.4V (2020), with a same-thread self-correction in February 2020; low-gain maximum 2.5V (2018, 2019), just over 3V (2019) or 3.3V (2019). This archive does not reconcile them.
• The January 2024 statement about Qutest's settings was made in the Mojo 2 thread.
• No statement from him recommends a setting for a named amp model.

Topics: Volume, gain and output level, Pre-amps, power amps and amplifier choice, Controls, indicators and remotes