Rossini vs. Preamp Volume Control and Setting

Hello,

My Rossini is currently feeding (at full volume) a Soulution preamp. At one point, I did experiment without the preamp in the path, however, to my ears, with preamp sounded better.

My question is this. Now that i’ve settled on a preamp in the path, do the Rossini volume settings matter? I’ve read on a few publications that it’s better to let the preamp do as much around volume control. Also, in theory, the lower I set the Rossini volume, the less work it has to do and the more it can concentrate on D/A conversion?

Thanks,
Udi

Check out this discussion regarding volume control and preamp

You should set the Rossini to full vol. do not turn the vol down on the Rossini, otherwise you will loose bit depth resolution!
You can clearly hear the difference with your own ears.

Also set the Line output from Rossini to 6 volts in setup meny for the best S/N ratio possible.

I would not recommend doing that by default! Some Pre-amps can overload as they have input sensitivity of just 2V.

I would highly recommend people read the dCS manuals, there’s a clear warning;

Thank you for this. I did notice this warning in the manual and set my line output to 2v. So, otherwise, everyone agrees that setting the Rossini volume to maximum is likely to yield best SQ?

In my opinion, the best SQ would be achieved by checking what’s the exact input sensitivity of your particular Pre-Amp and then matching to that as closely as possible on the dCS DAC.

Digital volume controls work by “discarding” bits.Therefore when set at 0.0 nothing is discarded and you have maximum resolution. However it is unlikely that you would actually be aware of any subjective loss of sound quality until the reduction in level below 0.0 is significant. By then, however, the loss of volume may be such that you would not actually be aware of the quality loss. I have listened and listened to the effect on sound quality that setting the control well below -20dB brings and , frankly, have nothing to report. It just sounded quieter as it should.

As for the voltage settings these are limited in scope on the Rossini and exact matching rather than approximate matching is not possible. The 0.0 figure refers to dBfs ( decibels full scale). That is if the programme material has a section at the maximum recordable level (0.0dBfs) then the Rossini will put out a voltage of 2 or 6 volts , depending upon your voltage selection. Of course the actual voltage level will vary in accordance with the recording level moment to moment and a 2 or 6 volt output may rarely or only briefly be encountered in practice ( partly depending on genre of music).

That figure of 2V and the recommendation to use it is not a random figure but is based on the industry standard for the voltage that CD ( and SACD) players should produce for a recorded level of 0.0dBfs. The majority of modern preamp line inputs are designed with something around that figure in mind for sensitivity. The need for 6V for a line input on a preamp would be, IMO, unusual. It may, however be appropriate for certain tube power amplifiers with comparatively low input sensitivity and where the DAC is directly connected ( no preamp).

Some old preamps, mainly dating from before the CD era, may overload even with a 2V input. dCS does cater for this circumstance ( and for some power amps with very high sensitivity) with e.g. the Vivaldi DAC which also offers outputs of 0.2V and 0.6V for 0.0dBfs recorded level.

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Just to add I have tired the Rossini direct in to the power amps (balanced) at 6v and it sounded great. By the way, 6V is better sounding than 2V. But the same into the Preamp albeit single ended was just a little better. So, I’m sticking with my Preamp with the Rossini set at 0dB.

You may find it so but that is not a universally applicable conclusion. It will vary for person to person and system to system. For example with my power amps and their 0.5V input sensitivity it would be impossible to use a 6V setting in practice without the volume control turned down to a level where a possibly audible loss of resolution would occur or by using an in-line attenuator, the latter a great way of screwing up the sound from my experience.

I am sure that dCS would tell you that the output signal at 6V from the DAC is identical to that at 2V except 7 or 8 ( or whatever the number is) dB higher.

Yep, agree with that.

Just what I am hearing.

What I love about the Mosaic app is that there are many settings I can try towards finding what feels good to me in my circumstances :slight_smile:

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Yes, but you will get the highest SNR ratio nevertheless, it is also confirmed in the Vivaldi DAC manual under Specifications where you only get the highest SNR output with 6 volt output .

You will hear distortion if you over-steer the input stage of the pre-amp.

If you turn down the digital volume to - 40 or -50dbs you can defensively hear the loss of bit-depht in form of digital distortion artifacts, but like dCS have stated the digital volume is pit perfect from -20db - 0db