Preamps can color sound considerably. Surprising?

Which is the ultimate reason for not using a pre when the DAC has a decent - and preferably analogue attenuator. DACs produce sufficient output voltage not to use a pre.

@holmz 

both are relatively rare cases and the majority of pres between attenuated dacs and power amps add distortion and little else

It‘s funny how people argue about this subject. Attenuation and amplification are fundamentally different and the simple fact of the matter is that dacs only require the former. So what may be useful in amplifying a phono signal with rare exemptions become distorition when a dac is used.

@atmasphere,

could you kindly also get into the differences between attenuation and amplification? It seems hard to get across that most dacs only need the former whereas adding a pre by definition adds distortion. (While this may run counter to commercial interests, a degree of intellectual purity seems desirable in this discussion…)

@holmz 

my Dac is an Antelope Zodiac Platinum with a relay based attenuator and an output impedance of 56 Ohms unbalanced into my Wavac EC 300b power amplifier with an input impedance of 100kOhms. Hard to see where the problem might be with a 200x span. I’d love to try Ralph Carstens ClassD monos on balanced; this raises the Zodiac’s output impedance to 112 Ohms for his 100kOhms input impedance. Most problems discussed around attenuators deal with marginal situations, which on modern designs to my knowledge are rare. Your last sentence only applies to digital attenuation, which is lossy.

@atmasphere,

many thanks for answering, a really helpful contribution. Am I right in saying that most digital devices are designed to have low output impedance?

@mrdecibel 

agreed, the discussion now seems to focus on the likelihood of impedance mismatchesbetween DAC and power amp, methinks. In attenuation mode, all a pre does is add distortion if impedances are properly matched. We are finally getting somewhere on this topic…