Quote Originally Posted by Rothchild View Post
I'm presuming that your pre has a volume knob on the front of it? If so, what I'm saying is that rather than level matching the cdp with the volume knob at the same place, take the lower input from the pi and make up for it by turning the volume knob on the pre up until the levels in the room are the same as with the cdp.

Obviously the output level of the Pi is driving the input level of the pre, there will be an optimum value for this - too low and the pre has to do too much work, too high and the pre inputs will start to distort. Given that an amount of this is about satisfying an audiophile tendency, I'm thinking that having the pi set up to do no digital gain changing but pushing the analogue output level and then making up the difference with the expensive gain in your pre-amp would be preferable than 'messing with your bits' (via the PCM control).

Unfortunately this will make comparing a little harder as it will be difficult to match the sound level in the room and most research seems to show that even with tiny differences in volume listeners will prefer the louder source.
Ok, I get what you mean now. I will experiment a little further with it.

However, in my system, there's quite a discrepancy between the output of my Sony DAC and that of the IQ Audio, equating to five clicks on the volume knob of my preamp [I have a 100k DACT stepped attenuator on the Croft - not sure of the db difference between each click, but there are 23 available positions], if the PCM level is set at 86 (with playback in Alsamixer at full), and consequently it makes the Pi/DAC sound somewhat 'soft' and anaemic in comparison.

Level-matching the Pi/DAC with the Sony, by setting the PCM level to 96, gives the former the required 'boost', in order for it to sound as 'big'/ballsy (whatever word you wish to describe it) as my Sony CDP/DAC, when playing CDs. What you're suggesting would probably work if the output/loudness discrepancy between the two sources in question wasn't as large.

Do you see where I'm coming from?

Marco.