DAC as an attenuator?

"09-01-14: Big_katydid
Zd542. The idea would be to use the DAC to attenuate CD signal into the preamp input so as not to relatively overdrive it, quite common with low sensitivity input line inputs."

Unless you have a very odd preamp, you shouldn't have any problems over driving it. Even though the DAC has a volume control, you treat it the same as any other line level source. It will say in the manual what settings are best when going from the dac to a preamp.

Of course it will work. I use my Eastern Electric DAC that way. It has an Alps analog volume and I use it to level match to my other sources. My pre ampis more linear at upper volumes with better control over small changes in volume. Digital attenuators may reduce the bits and thus may throw away resolution if dialed down. Analog volume controls should not but require better designs for linearity and noiseless function. At least that is my primitive understanding.

Yes, this will work even with digital volume. The balanced input on my integrated amp will overdrive with more than 3 volts or so. Since most balanced outputs are 4 volts or more, I use the digital volume control in the dac to reduce the output gain by 6 db (or 1 bit). Yes, you are throwing away 1 bit of information if using a 24 bit volume control, but it is not audible to my ears with the two dacs I have tried this with.

I may be wrong, but here is how I understand it if listening to 24 bit material. 24 bits is equal to a SNR of 144 dB. Pretend your dac was cabale of a SNR of 120 dB after the digital to analog conversion which is equal to approximately 20 bits. If you're only throwing away 1 bit of info, you still have 23 bits to work with which is still greater than a SNR of 120 dB or 20 bits.

Short answer, it works and it works well in my experience if you plan to reduce the volume slightly to adjust the output gain.

Johsti,

I have digital volume controls on my CD players and I can't hear any difference is SQ at low volume settings either. But if you are worried about over driving a preamp, you may have some global gain settings somewhere on your DAC or CD player. Mine do, but to access them I have to open them up and set some dip switches they give you. Its a very useful feature but quite often people that have these players don't know about it.

thanks for the responses all.

Definitely something to consider to reduce gain at the preamp input. Despite my amps quoted 1V input sensitivity I still find some CD's get 'shouty' at around the 8:30 position on the amp and at that point anything louder becomes unbearable, I have tried experimented with attenuation with my laptop as a source and it definitely helps once that lower part of the volume range is passed, if it doesn't 'shout' by 10 oclock then volume increase after that is much more linear and sounds good.