I currently re-samples everything in Roon and Audirvana to 24/48 before outputting the signal to my Lumin U2. I do this because I prefer letting Roon and Audirva do the conversions rather than doing it in my active speakers that perform all DSP on 24/48 signals. I simply think SQ is marginally better this way (using “Precise linear phase” re-sampling filter in Roon and similar in Audirvana).
However, since I also use the U2 for TV-sound sent over AirPlay from my Apple TV 4K, I have activated the re-sampling in the U2 in order for the signal from the Apple TV to be converted to 24-bit.
I am primarily using the Leedh volume control in the U2 with the DSP volume in the speakers fixed at – 15 dB (in order to avoid the lowest range in Leedh that is not sufficiently granular) and I normally listen at very low level, between -45 to -55 dB.
Now to my question:
Sending 32/48 signals from Roon and Audirvana to the U2 sounds audibly different compared to 24/48. The biggest difference is in the bass where 24-bit sounds rounder and 32-bit leaner and more staccato. A bit similar to comparing ported and sealed speakers in the bass region.
So, my question is: Does the Leedh attenuation work in 32-bit if incoming signal is 32-bit, or is the signal first converted to 24-bit since I have activated the re-sampling to 24-bit in the U2. That is, where is any re-sampling to 24-bit taking place in the U2. Before or after Leedh attenuation?
I have never managed to get answers to the following two questions so I try again:
Q1: If I send a 32-bit stream from Roon to my Lumin U2 and output the signal from the U2 over AES/EBU, is the signal converted to 24-bit (the maximum for AES/EBU) before or after attenuation by the Leedh volume control?
Q2: Does the stage at which the 32-bit signal from Roon is converted to 24-bit (i.e. before or after Leedh attenuation) depend on whether I choose “Native” or “24 Bit” in the “PCM Output Bit Depth” menu in the Re-Sampling settings?
After. The 32 to 24 bit conversion is done at the very last moment just before output to hardware.
Please keep it as native. This is a legacy setting that is not meant to be used any more, with the exception that there were one or two users with 20+ years old design of 16-bit DAC who finds forcing it to 16 bit sounded better to them.
Thanks for the information. Just some feedback regarding the Leedh volume control. I don’t know if it is imagination/expectation bias, but to my ears converting all signals in Roon to 32-bit before outputting to my Lumin U2 (where I do all attenuation with Leedh before sending the signal to my active speakers) sounds better than sending the native sample rate from Roon (mainly 16- or 24-bit) to the U2. It also sounds better, i.e. higher resolution, than sending the signal directly from Roon over Ethernet to the speakers and attenuate using the 24-bit volume control in the speakers. My guess is that the Leedh volume control does a better job at deep attenuation and that the attenuation is done in 32-bit. I normally attenuate about 45-55 dB.