Pro-Ject Pre Box S2 Digital: MQA HW decoding at reasonable cost

[fgribas]

I'm sharing all my findings regarding power supply and softwares that I use with the S2D. Long post 

Power supply. I've tested: Included switching power supply, 5v powerbank, USB port from computer (additional port, not the USB data cable), iFi iPower 5v, grounded iFi iPower 5v, Chinese Linear Power Supply.

Based on my listening, the best ones are (in the following order): 1- grounded iFi 5v; 2- chinese LPSU; 3- ungrounded iFi 5v.

I already had an iFi iPower for the S2D and was happy with that (significantly better than the included PS or 5v powerbank). But I finally found a Chinese LPS that has a 5v USB output + 12v output and also a 115v/230v switch. I have a 12v mini PC that I will use as an audio endpoint for Roon/HQPlayer. So a single linear power supply with 12v + 5v is what I wanted. This is the one I found: https://www.aliexpress.com/item/DAC...-linear-thermal-power-supply/32923450663.html

I ordered one, and while it was on the way, I decided to try the JSGT (John Swenson's Ground Technique) on my iFi iPower. Bottomline is: all switching power supplies suffers from leakage current. Linear power supply blocks most of leakage current. iPower has a ultra low noise output across the audio bandwidth. But iPower is still a switching power supply and suffers from leakage current.

The technique is basically connect the negative pole of the power supply to the ground pin of the same power outlet (or power strip) where the power supply is connected.
More details here: https://audiophilestyle.com/forums/topic/37034-smps-and-grounding/

I made my mod a little different (aesthetically better) than the original idea of using additional female connector + male connector. Mind that these 2 socket male plugs must be connected to the same power outlet (or power strip).

This grounding made a great improvement. The Chinese LPS arrived later and it sounds good, it's sturdy and well-built. However the grounded iPower still sounds better.

Software and configuration. I find DSD128 better than DSD256 or DSD512 on the S2D. I thought it strange and looked for explanations. I found out this: https://positive-feedback.com/audio-discourse/raising-the-sample-rate-of-dsd-is-there-a-sweet-spot/

It's an article from an engineer involved in the creation of SACD at Sony. The article is from 2015 and now we have DSD256 or DSD512 capable hardware, like our Pro-Ject S2D. But capable doesn't mean optimized. Rough analogy: it's like a video-game capable of running a 4K game, but at 15 fps. I think DSD256 (at least on the S2D) still introduces some kind of distortion or artifact, because it doesn't sound as natural as DSD128. But again, this is all based on my listening impressions. One fact is that DSD128 already solves the problem of audio bandwidth noise that DSD64 presents.

Source material: I mainly use Qobuz and Tidal, both on Roon. HiRes from Qobuz is great! MQA from Tidal is nice, as long as we decode only the 1st stage on Roon and then upsample on Roon or HQPlayer. Then I upsample to DSD128 on HQPlayer, using poly-sinc-short filter and DSD5v2 modulator. The filter is a matter of choice, but it seems that DSDv2 is the "correct" modulator for this DAC. I came to this conclusion only after having such a clean power supply. Roon upsampling instead of HQPlayer does a good job. HQPlayer upsamples better, but Roon using DSD128 "Precise, Linear Phase" filter and "5TH order (CLANS)" modulator comes close. I also use parametric EQ on Roon, and it squeezes the best out of my Shure SE846 IEMs.

And the final piece after upsampling is JPlay Classic (only the driver, not JPLAY femto). I use Ultrastream engine, 500 Hz DAC Link and Kernel Streaming. 1000Hz DAC Link sounds even better, but it needs a dedicated audio computer so it doesn't have dropouts, but currently I'm using my work PC to everything. I also use Fidelizer software. I bought Audiophile Optimizer but still haven't tested because it also needs a dedicated audio computer. Using my mini PC for that is the next step.

And finally on the Pro-Ject Control Panel, the lowest available ASIO Buffer Size, and Safe Mode unchecked.

[fgribas]

@Miska is it possible to make sinc-M output the same rate as input? 

 

When I use a Dragonfly DAC (max 96 kHz) playing 96 ou 88 content, it actually downsamples to 44 or 88.

[fgribas]

19 hours ago, fgribas said:

@Miska is it possible to make sinc-M output the same rate as input? 

 

When I use a Dragonfly DAC (max 96 kHz) playing 96 ou 88 content, it actually downsamples to 44 or 88.

 

ooops, posted on the wrong topic, sorry 🤦‍♂️

 

[fgribas]

51 minutes ago, Jud said:

I don't suppose we could convince you that non-MQA-encoded material (for example, downloads, Qobuz) actually sounds better, eh?  😉

 

MQA discussion is a long long story 😄

 

But in a nutshell, MQA is better than redbook when you only do the 1st unfold by software and then upsample with good filters (with HQPlayer for example). Pure MQA (1st unfold + MQA own filter) can sound better than redbook, or the same, or even worse.

 

Qobuz and every other real hi-res source is better than MQA, no doubt about it. I currently have Tidal and Qobuz subscription, both used on Roon. And I'm very happy with it and my S2D.