The Ultralite signal is 8.6v, Purifi amp is input without pre-gain 10.59v, so 81.2% power. But now this is made irrelevant by..
Very appreciative to know this. Pre-gain required for both options.
I was arriving at this as well. DAC8 excels at SNR and clearly multi-tone test. Since I'm already using NC400 for 7.1, I'll upgrade to the DAC8 (when available) and wait for measurements on the new Purifi 1ET7040SA.
I appreciate learning so much through exchange of ideas. This forum continues to amaze me. Being fully informed of component choices makes final selection more assuring and way more rewarding.
EDIT: Just ordered DAC8. Super excited!
I've been meaning to write a longer post explaining how to compare noise performance between different DAC and gain settings with the Purifi. Everything shown below is based on values measured by Amir but should be pretty close to spec'd performance for the equipment in question.
DAC8 pro w/ 1ET400A at 27.5 dB gain
DAC SNR = 122 dB at 3.3 V
DAC residual noise = 3.3 x 10^(-122/20) = 2.62 uV
amplified residual noise = 2.62 x 10^(27.5/20) = 62.2 uV
amp SNR at 5 W in to 4 ohm = 105 dB
amp residual noise = sqrt(5 x 4) x 10^(-105/20) = 25.1 uV
system residual noise = sqrt(25.1^2 + 62.2^2) = 67.1 uV
system SNR at 5 W in to 4 ohm = 20 x log (4.47 x 10^6 / 67.1) = 96 dB
Ultralite Mk5 w/ 1ET400A at 12.8 dB gain
DAC SNR = 121 dB at 8.6 V
DAC residual noise = 8.6 x 10^(-121/20) = 7.66 uV
amplified residual noise = 7.66 x 10^(12.8/20) = 33.5 uV
amp SNR at 5 W in to 4 ohm = 110 dB
amp residual noise = sqrt(5 x 4) x 10^(-110/20) = 14.1 uV
system residual noise = sqrt(33.5^2 + 14.1^2) = 36.3 uV
system SNR at 5 W in to 4 ohm = 20 x log(4.47 x 10^6 / 36.3) = 102 dB
So about a 6 dB improvement in system SNR when using the Ultralite Mk5 with the low gain setting. Interestingly enough if you went with an implementation with a mid-gain setting like this ->
https://www.audiosciencereview.com/...ics-hpa-s400et-review-stereo-amplifier.32014/ and used the Okto you can get the same noise performance
DAC8 pro w/ 1ET400A at 20.2 dB gain
DAC SNR = 122 dB at 3.3 V
DAC residual noise = 3.3 x 10^(-122/20) = 2.62 uV
amplified residual noise = 2.62 x 10^(20.2/20) = 26.8 uV
amp SNR at 5 W in to 4 ohm = 107 dB
amp residual noise = sqrt(5 x 4) x 10^(-107/20) = 20.0 uV
system residual noise = sqrt(26.8^2 + 20.0^2) = 33.5 uV
system SNR at 5 W in to 4 ohm = 20 x log(4.47 x 10^6 / 33.5) = 102 dB
Although honestly all of these systems are very low noise and unless you are using extremely sensitive speakers you will not have any noise issues. For reference I like to keep total residual at less than 200 uV so these are all well below that.
Michael