Pro-Ject Pre Box S2 Digital Impression Thread
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zpierce

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I've been using this DAC for the past month or so. Works great connected to my iMac playing Tidal Hifi and Masters. I also use my iPhone frequently with lightning camera adapter and this often takes unplugging and replugging into the phone 2-3x before it connects and plays through the DAC. Not a huge deal, but an annoyance. Didn't have this issue with my Dragonfly Red when I used to use that with the phone.
 
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fgribas

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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.
 
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Stereomojo

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Just quickly read through this thread ... thank-you for everyone's thoughts. I'm considering an S2 for office desktop role connected to an iMac (HiSierra) and I have a couple of questions. Has anyone any thoughts about using AEON Flow Open headphones (13 Ohm/95dB) with the S2 ? Also, is there any advantage to using an UpTone LPS-1 through USB via a pigtale power line (versus getting a DC-Jack/USB adaptor into the normal power inlet) ?
The Aeon Flows definitely do NOT play well with the SD2. I have a pair. There's distortion from the impedance mismatch.
 
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Thank-you @Stereomojo ... good info for prospective purchasers of the SD2. Since that post I have settled on a Schiit MJ2 and a LYR2 to pair with the AFO with good results. I concur with the thoughts of others that the AFO prefers a Hybrid amplifier to get the best out of it.
 
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Any ex-ifi user here? I currently own a ifi idsd nano, considering pro-ject pre box s2, is it a notable upgrade? or I should stick to my nano for now? I don't play MQA, and mostly play through my speakers. Any opinion would be great, thanks!
 
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Any ex-ifi user here? I currently own a ifi idsd nano, considering pro-ject pre box s2, is it a notable upgrade? or I should stick to my nano for now? I don't play MQA, and mostly play through my speakers. Any opinion would be great, thanks!
I have a 1st edition iFi iDSD and I do like the S2D better. However, I have issues with the S2D dropping its signal quite often; a problem that I never had with my iFi.
 
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@fgribas To clarify, while testing these power supplies are you also feeding signal via usb? I noticed that the manual actually recommends unplugging the mains power when running via usb because it can exhibit some kind of interference when fed by dual power supplies. I'm not sure if they're referring generally to ground loops, or if it's a characteristic of this specific device.

That being said I'm curious what your setup is because I have a 5v iPower that I'd like to run, but I'm primarily feeding via usb.
 
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@fgribas To clarify, while testing these power supplies are you also feeding signal via usb? I noticed that the manual actually recommends unplugging the mains power when running via usb because it can exhibit some kind of interference when fed by dual power supplies. I'm not sure if they're referring generally to ground loops, or if it's a characteristic of this specific device.

That being said I'm curious what your setup is because I have a 5v iPower that I'd like to run, but I'm primarily feeding via usb.
The manual refers to the stock power supply, which is intended only for use with coaxial or optical input.

The designer has (on other forums) recommended linear or battery power supplies to avoid such problems and to improve sound quality.

Before his relationship with Pro-Ject ended, he helped them develop the Accu Box S2, Accu Box S2 USB, and Power Box S2.
 
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Any ex-ifi user here? I currently own a ifi idsd nano, considering pro-ject pre box s2, is it a notable upgrade? or I should stick to my nano for now? I don't play MQA, and mostly play through my speakers. Any opinion would be great, thanks!
I have a nano iDSD BL and enjoy it very much. IMHO you should give MQA a chance if you have access... like through Tidal. The difference might not be all that much if you do not take advantage of MQA, because the main advantage, again IMHO, is that you get full hardware/software decoding of MQA in the Pro-Ject.
To see if you like MQA, I would pick one of your most well known albums... mine are Beatles: White, Sargent Pepper, Fleetwood Mac: Rumors etc. and listen to one non MQA then turn right around and listen to it MQA.
OH... I only listen to music with headphones which will color my opinion.
 
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bunkey

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Thanks for sharing your experiences! I've got my S2D today(stock v2.12), love the sound so far, it's more controlled and a lot more resolution than my original ifi nano.

However I'm having trouble with DSD playback, DSD128 flac is fine, but when I try some DSD256 DSF file, I get constant pops. I'm using Foobar2000, previously configured for ifi nano. Tried google my way out, found this pdf http://www.hificlube.net/media/8805/pre-box-s2-digital-user-manual.pdf
but it seems a bit out of date or something, my new download of foo input sacd don't have ASIOProxyInstall in the zip, so I can't really follow that instruction.

Edit:Nevermind, I got it working after update to latest plugin(sacd & dsd processor).

One more question, how do you turn off this thing? Display still on even when PC off.
 
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One more question, how do you turn off this thing? Display still on even when PC off.
If the USB port still provides power when the PC is shut down, your PC probably has a "charge phone while PC is off" feature unique to your PC/motherboard brand and you'll have to research how to disable it. If it only stays on when asleep, that's a little easier to search for, but both cases Google is your friend once again.
 
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bunkey

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If the USB port still provides power when the PC is shut down, your PC probably has a "charge phone while PC is off" feature unique to your PC/motherboard brand and you'll have to research how to disable it. If it only stays on when asleep, that's a little easier to search for, but both cases Google is your friend once again.
Thanks Left Channel!

I'd like to share what I found while playing with this little beast for day 1, not sure if anyone has found a way to get around the v2.12 bug, I also notice the lower volume/thinner sound switch from MQA playback, so this is what I do, and it seems to work for me, after playing MQA file, play a DSD256 file, then I'm good with any standard file. I could be wrong, only a short testing, thought I'd share anyway. BTW I'm using foobar2000 for playback.
 
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Thanks Left Channel!

I'd like to share what I found while playing with this little beast for day 1, not sure if anyone has found a way to get around the v2.12 bug, I also notice the lower volume/thinner sound switch from MQA playback, so this is what I do, and it seems to work for me, after playing MQA file, play a DSD256 file, then I'm good with any standard file. I could be wrong, only a short testing, thought I'd share anyway. BTW I'm using foobar2000 for playback.
Good tip, thanks. MQA → DSD → PCM. That's assuming you like the Optimal Transient filter. As you may know you will not experience that bug when using any other filter, and also after extensive testing the developer of HQ Player recommends selecting the Fast Rolloff filter and enabling Distortion Compensation. Do you have a preference for Optimal Transient over Fast Rolloff? Some of us don't hear much difference between them anyway.
 
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Good tip, thanks. MQA → DSD → PCM. That's assuming you like the Optimal Transient filter. As you may know you will not experience that bug when using any other filter, and also after extensive testing the developer of HQ Player recommends selecting the Fast Rolloff filter and enabling Distortion Compensation. Do you have a preference for Optimal Transient over Fast Rolloff? Some of us don't hear much difference between them anyway.
I haven't got the chance to play around with filters yet, just set to fast roll off now, but I can't figure out how to enable Distortion Compensation?! Sorry I'm a S2D noob, tried pretty much all buttons, but nothing changes under Munu, up down arrow only shows different info, tried OK button on remote only bring back to volume display. Manual included is poorly documented. Can someone please tell me how to enable Distortion Compensation?

Edit: Solved, it did mentioned on manual, using left right button to change.... my bad.
 
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