Sprout and Upsampling


#1

Folks:

I’ve spent a few weeks now experimenting with the Sprout connected to my Mac Air via USB using Bitperfect software (and iTunes). From my subjective point of view, disabling Bitperfect upsampling sounds best with the Wolfson DAC that Sprout has. I tried using each SRC algorithm Bitperfect supports along with enabling/disabling the “powers of 2/4” feature. Particularly with native 16/44.1, sending the stream at 24/44.1 (rather than 176.4 or 192) seems to sound best. Note that I haven’t found this to be the case with other DACs (or other DAC / clock implementations).

I invite others to experiment and share their impressions (with the same or other streaming software, naturally).


#2

Is the DAC in the Sprout up-sampling?

If so, how would you shut it off?


#3

Exactly what a company’s DAC does internally is typically not documented in detail. The Wolfson DAC in the Sprout can do 24/192. All I can know for sure is that no SRC is occurring in my playback software. Bitperfect is presenting 24/44.1 (in the case of CD quality PCM files) to the USB Audio driver. That driver sets up the USB Audio channel appropriately. Inside the Sprout, some USB firmware sets the DAC sample clock to be an whole number fraction of the master clock to signal the rate at which it will presenting samples. What happens inside the DAC itself is not typically documented in detail but it’s reasonable to imagine that internal upsampling occurs prior to presenting a high speed bitstream to a Sigma Delta conversion process. Unlikely this could be disabled but depending upon the DAC design you could probably present a slow enough master clock that the DAC would only sample at low sample rates (below 96)…


#4

I don’t upsample either using JRiver. I send all the music to Sprout in its original resolution and let the Sprout do it’s magic. That’s one of the main things we spent our money for, right, A quality DAC? I figure its DAC is better than any software such as BitPerfect or JRiver.


#5

Andrew, I agree. I turn off upsampling immediately in Bit Perfect.