This article seems to answer my question. But what do I lose without the attenuator?
https://forum.rme-audio.de/viewtopic.php?id=25399

I'm lost in the terminology. What's dBu vs dBV vs dBr vs dBA vs dB?

Im often down to -30 to even -50. Any volumecontrol, be it pot, resistor, digital will have a: too low -- sweetspot -- too high setting in relation to your hearing. The DAC fs does one heck of a job to WIDEN that sweetspot via Autoref levels, PEQ, B/T and the intelligent loudness control. You wont hear any noise qoute manual "..it wasnt there in the first place".

You can use Ramses charts to get max SNR for some serious listening being confident that you get absolutely top performance in your session. Or just for casual listening, watching a downloaded movie with mp3 encoding or youtube "..it sounds fine to my ears." If its good, its good, right.?

IMHO buying another HPamp/attenuator is waste of money simply because you dont need it. DAC fs can go stellar if you like or you can set it up so it doesnt challenge your attention span, more like background listening.

The digital volume tech has come under some attack. These are mostly just haters and agents of other brands. They cant touch this with their own gear or technology and they know it. An expression of fear

My advice is to get to know your device. Read the manual. Read post in this forum. The DAC fs has some learning curve and it takes some listening time sorting out preferences to the multitude of settings. Knowing what I know I would put my hard earned cash on another set of headphones. If u have a serious level problem these can sort it out adjusting with impedance and sensivity.

Elfred,

See section 30.2 of your User Manual.  Here, we can find the SNR at the various Ref Levels, and means of connection.  From this, we can subtract our Vol Setting and derive the value of our expected SNR.

-5 Ref Level (unbalanced) equals 117db SNR.  Subtracting from this your Vol setting (-30) equals -87db.   That's really quiet, but the data should help you more easily see the effect of Vol Setting, and why Auto-Ref is such a great functionality!   

All that said, you don't NEED attenuators, because if you don't hear noise...there is no noise to be concerned with.

I like my Vol to be in the -15 range, but that's me.  Further, very low Vol setting requirements for normal listening allow for the possibility of the user inadvertently sending their Amp/Speakers a signal level far in excess of what they can handle.   If it's getting loud at -30db, imagine what 0db would sound like?  Ouch!!  Ooops!!!

This will sound exactly like Repair Bills!

Attenuators then to some degree act as a Safety barrier to prevent overloads downstream.

Alternatively, you could just lower the input sensitivity of your Amplifier, and achieve the same result.

Best,

Curt

0 dBu is 0.775 volt RMS.

0 dBV is 1 volt RMS

dBr is context dependent.

dBA means that A-weighted filter is used. Another popular filter is C filter: less low and high cut than A. For low level noise assessment, A filter is popular. For moderate level music sound, C filter is popular. I guess Z filter means flat in audio band.

For voltage amplitude, 20 X log10( V1/V2 ) is the dB figure of the ratio V1/V2. For example, if 0.1 V RMS input results in 1.0 V RMS output by an amplifier, the voltage gain of the amplifier is said to be 10, or in terms of decibel, 20 dB from the calculation 20 X log10( 1.0 / 0.1 ) = 20 X log10( 10 ) = 20.

Refer to section 19.3 of the User Manual

Based on the Vol, and Ref Level indicated by the Poster, my Math is in agreement with the method of calculation explained in the manual.

Curt