Up-Down-Sampling (UDS) removes CD dither which manifests as a gritty sound from the tweeter. To use UDS, I up-sample to high multiple of the CD sample rate, e.g. 2,822,400, and then down-sample to the highest rate my AD1865 DAC will accept, e.g. 176,400. The process is accomplished using Foobar and two instances of the Sox resampler.
No doubt you hear a sound you like but it's more likely the result of using two instances of the Sox resampler instead of removing dither and leaving the rest of the signal untouched. Sox resampling is probably just lopping off the high end which sounds better with your DAC, speakers and other electronics. Music lovers who use the same DAC will benefit from your experiments.
This article should be read before diving into the Steve Hoffman and Bob Katz links
What Is Dither and Does It Matter?https://www.masteringthemix.com/blogs/learn/what-is-dither-and-does-it-matterSoftware to Remove DitherA discussion in the Steve Hoffman Music Forum says it can't be done with out specialty software and even then removing dither shouldn't be done because it plays an important role. Yes, dither adds noise but modern noise shaping moves it higher where it can't be heard.
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About the only way to remove dither -- which is intentionally-applied low-level digital noise -- would be to use NoNoise or a similar process, which would introduce problems of its own. You'd also wind up with more distortion, since that's one of the problems that dither is designed to solve."https://forums.stevehoffman.tv/threads/software-to-remove-dither-from-hdcds.118152/The Steve Hoffman Music Forum thread mentions an article about dither by Bob Katz. The article is no longer available on Katz's web site but it is available on the Internet Archive:
https://web.archive.org/web/20071218185621/http://www.digido.com/bob-katz/dither.htmlBob Katz writes:
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Obtain the disc Best of Chesky Classics and Jazz and Audiophile Test Disc, Vol. III, Chesky JD111. Track 42 is a fade to noise without dither, demonstrating quantization distortion and loss of resolution. Track 43 is a fade to noise with white noise dither, and track 44 uses noise-shaped dither (to be explained). Use Track 43 as your test source; you should be able to hear smooth and distortion-free signal down to about -115 dB. Then listen to track 44 to see how much better it can sound."
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When feeding processors, dither the output of the processor to a 24-bit word. Dithering always sounds better than truncation without dither."
Truncation without dither is what you might be doing when downsampling to 176,400.
Instead of using Foobar and Sox for upsampling try
HQPlayer, it is the state-of-the-art upsampling software. It is free to try, the software will function for 30 minutes at a time without a license key. HQPlayer is an integral part of $2795 Ferrum Wandla DAC reviewed and measured in the Feb. 2024 Stereophile (review will be online soon).
https://www.signalyst.com/consumer.htmlHQPlayer is a high quality audio player for 64-bit Windows, Linux and macOS.
HQPlayer also features several user selectable high quality resamplers as well as user selectable dither/noise shaping algorithms and delta sigma modulators.
Some of the more affordable D/A converts have suboptimal digital and analog filters, while still having support for higher sampling rates. The effect of this can be reduced by applying high quality upsampling in software before feeding the signal to audio hardware at a higher rate. This moves the artifacts of the suboptimal hardware to higher frequencies, away from the audio band.
HQPlayer includes:
Resampling filters:
40 linear phase
3 intermediate phase
11 minimum phase
4 impulse optimal
3 closed form
Dithers and noise-shapers:
4 dithers
5 noise shapers
Delta-Sigma conversion:
30 modulators
68 oversampling filters (64x - 2048x)
Direct rate conversions, 3 algorithms
Digital volume control
Convolution engine
Parametric equalizer
Routing and mixing
Jussi Laako, HQPlayer's developer, wrote an excellent article how HQPlayer works along with it's many filter and dither settings:
HQPlayer Resampling Filter Setup Guide for the Ordinary Personhttps://audiophilestyle.com/forums/topic/13071-hqplayer-resampling-filter-setup-guide-for-ordinary-person/#comment-175928Audiophile Style has a big HQPlayer thread that will answer any of your questions. Sign up and Search for "dither" and pick "This Topic" from the drop down menu.
https://audiophilestyle.com/forums/topic/19715-hq-player/#commentsAsk a question in the thread about if your method of removing dither is a good idea. Jussi Laako is Miska in the forum. Everyone is friendly and I have never read a sarcastic or condescending reply to a question.
The only free recordings I know of that compare dither to no-dither is the download of "Funeral March Of A Marionette" from Gounod Faust/Bizet Carmen Suite with Alexander Gibson conducting the Royal Opera House Covent Garden Orchestra, this hugely dynamic recording will test your system.
https://www.audiocircle.com/index.php?topic=188454.msg1973417#msg1973417What We Hear With DXD 32-bit Files (Free Sample Downloads)https://positive-feedback.com/reviews/music-reviews/what-we-hear-with-dxd-32-bit-files/Free downloads: each of the four tracks are 4:35 minutes long, 24-bit and 32-bit with 3 tracks in PCM and 1 in DSD.
352.8kHz/32-bit: Track 8, "Funeral March Of A Marionette"
352.8kHz/24-bit: Track 8, "Funeral March Of A Marionette"
352.8kHz/24-bit TRUNCATED, NO DITHER: Track 8, "Funeral March Of A Marionette"
1-bit DSD256: Track 8, "Funeral March Of A Marionette"
The articles author is also considering comparing A/D digital processors:
"Is what I'm hearing only a function of how Pyramix processes the files it outputs when using Pyramix Album Publisher? Will a similar comparative result show its head when listening to files processed with
HQPlayer Pro (NativeDSD files) or Weiss Engineering Saracon (TRPTK files from their own download site) or some other software?"
