ProtoDAC TDA1387 X8 project

[hifinet]

I am having some second thoughts about the 100R I/V resistor plus a preamp gain stage. Yes, there is more bass and better detail, but at the expense of some damage to the openness and soundstage. In general, if you can get by without a preamp gain stage, that is preferred. If you have the extra gain to use the 100R I/V resistor, you probably would be better off eliminating your preamp entirely and use a high quality pot, stepped attenuator, etc. and use the 420R I/V resistor. A voltage gain stage will always add some coloration.

With this DAC chip, there is not that much to improve regarding THD, which is about 0.01% with 420R and 0.006% with 100R.

The solution might be to add a buffer for better impedence matching. Talked about it months ago. A buffer tends not to color the sound.

I think that I should try four modules with 100R I/V. Distortion will still be at the 0.01% level, but output impedence will be lower. It will also keep the DAC relatively simple. Noise will be reduced. 3dB for each doubling. @eculcea in this post #681 used two modules stacked with 200R I/V resistors (2200uF times two decoupling caps) and found "a better and more detailed sound at the lower frequencies." That would be the expected result with better impedence matching.