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Review and Measurements of Topping DX7s DAC and Headphone Amp

Jonny

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Here's what I wrote about this back in September post #272 re my iMac via USB using DX7s:

I also wanted to report on interesting findings on using Audirvana and HQPlayer/Roon on the DX7s via USB on an iMac. My music library is mostly ALAC 44.1/88.2/96/176/192. On Audirvana Plus (latest version) I can get PCM upsampled to 705/768, but I get dropouts and clicks at that setting. PCM upsampled to 352.8/384 works fine and sounds very good. On DSD upsampling of PCM files, I can get to DSD256 but again I get clicks and dropouts. No such problems when upsampled to DSD128. On the DX7s in Audirvana Plus upsampled to DSD128, I get strong sibilance on female vocalists, but less so on PCM 352.8/384.

Using HQPlayer/Roon on the DX7s, I can easily upsample PCM to705/768 and DSD256 (the max available on a Mac) without any dropouts or clicks, and no sibilance.

Now, in Audirvana I still can't upsample PCM beyond DSD128 without dropouts, but I can upsample PCM to 705/768 without problems. No clicks either way. And that is using tracks in mostly ALAC on my hard drive or streaming Flac via Tidal or Qobuz. No change or problems at all in using HQPlayer/Roon or Roon alone using DSD256 or PCM 705/768. HTH.
Yes I'm having no problem at all playing DSD in Roon just on it's own without HQ player.
 

RayDunzl

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Can someone confirm this?
I would find that highly unlikely, since it is powered via AC mains.

The complaint concerned a suspected grounding problem.
 
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I would find that highly unlikely, since it is powered via AC mains.

The complaint concerned a suspected grounding problem.
Well, is it possible that the AC mains powers the amp portion, where the DAC portion is powered by USB?

I have a grounding problem with my computer for sure. In fact, I have a terrible noise problem.

Amirm said that a good DAC with proper filter should filter out all USB noise problem and ISO Regen is not needed.
Topping DX7s should filter out all noise issue since it's a good high quality DAC, why is IFI Idefender 3.0 and IFI ipower needed?

I am so confused? Do we need ISO Regen or IFI iGalvanic afterall?
 

RayDunzl

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Well, is it possible that the AC mains powers the amp portion, where the DAC portion is powered by USB?
Then it would require some sort of internal sensing/switching to provide power to the DAC from the internal power supply when used with the Optical, Coaxial, or AES inputs, instead of the USB.

Which makes no sense to me.

1544163606866.png


(I get to be wrong, but...)
 

amirm

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RayDunzl

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amirm

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I have seen this in a few DACs but otherwise, it would be very unusual for an AC powered device to work this way.
 
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As a DX7s user, I can confirm that there isn't the slightest hint of a USB noise issue when used in conjunction with a mains-powered computer with absolutely standard earthing arrangements – no fancy isolation and a $2 certified USB2 cable!

It wouldn't surprise me in the slightest if there were an awful lot of people "out there" doing their very best to disparage this unit and many like it. I was (and remain) hugely impressed by its sound quality and I dare say that it is highly likely that there are many enthusiasts who, having spent thousands on DACs that sound no better, are a little peeved with the way the Chinese appear to be redefining the market for this kind of product.

Cynical note follows: this could be why many western high-end (i.e. high price) manufacturers are anxious to promote the MQA route – the licensing arrangements ensure a significant price differentiation in a world where the Chinese will soon be outclassing the value-for-money of western brands.
 
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Veri

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The Chinese are also jumping on MQA though, they just aren't there yet. In a year or so that also will no longer be a differentiator.
 
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As a DX7s user, I can confirm that there isn't the slightest hint of a USB noise issue when used in conjunction with a mains-powered computer with absolutely standard earthing arrangements – no fancy isolation and a $2 certified USB2 cable!

It wouldn't surprise me in the slightest if there were an awful lot of people "out there" doing their very best to disparage this unit and many like it. I was (and remain) hugely impressed by its sound quality and I dare say that it is highly likely that there are many enthusiasts who, having spent thousands on DACs that sound no better, are a little peeved with the way the Chinese appear to be redefining the market for this kind of product.

Cynical note follows: this could be why many western high-end (i.e. high price) manufacturers are anxious to promote the MQA route – the licensing arrangements ensure a significant price differentiation in a world where the Chinese will soon be outclassing the value-for-money of western brands.
Hi can you help me do a test?

Use DX7s using usb input from your computer. Start playing a song, then turn off the power of DX7s during the middle of the song and see if the song is cut off. This way we will know for sure whether DX7s DAC portion is powered by USB or by internal linear power supply.
 

amirm

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Hi can you help me do a test?

Use DX7s using usb input from your computer. Start playing a song, then turn off the power of DX7s during the middle of the song and see if the song is cut off. This way we will know for sure whether DX7s DAC portion is powered by USB or by internal linear power supply.
The Song cuts off;)
 
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And time domain response to a square wave:

Filter 1
View attachment 14400

Filter 2
View attachment 14401

Filter 3:
View attachment 14402

Filter 4:
View attachment 14403

Filter 5:
View attachment 14404

Filter 6
View attachment 14405

Filter 7
View attachment 14406
Hi everybody,
A new member here, although following the forum since long.
Thanks a lot Amir for all the specs and graphs, now right to my question:
DX7s lists the filters in the following order:
Mode 1: apodizing fast roll-off filter
Mode 2: minimum phase slow roll-off filter
Mode 3: minimum phase fast roll-off filter
Mode 4: linear phase slow roll-off filter
Mode 5: linear phase fast roll-off filter
Mode 6: brick wall filter
Mode 7: corrected minimum phase fast roll-off filter

According to my understanding, the impulse responses you have published don't correlate with this order. Just looking at your graph no. 4 gives a clear picture of minimum phase slow roll-off (no pre-ringing, short post-ringing), where Topping's manual states linear phase. Further, looking at the filters 6 and 7, they seem to me clearly inverted: I would guess no. 6 to be corrected minimum phase and no. 7 to be the brick wall.
Actually your line-up corresponds perfectly with the order in the ES9038q2m data sheet on page 57: http://file2.dzsc.com/product/18/05/25/829029_170233543.pdf

My question: is it possible that Topping messed up with the names of the filters? Thanks for the clarification.
 
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is it possible that Topping messed up with the names of the filters?
I'd say it was exceedingly likely :eek:

FWIW I find the audible difference between the filters to be very slight with, possibly, a small preference for 4 and 5 (whatever they're called) over the others. But I must stress that the audible difference is so minimal that I'm not going to loose sleep fretting about it.
 
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I'd say it was exceedingly likely :eek:

FWIW I find the audible difference between the filters to be very slight with, possibly, a small preference for 4 and 5 (whatever they're called) over the others. But I must stress that the audible difference is so minimal that I'm not going to loose sleep fretting about it.
Thanks a lot for the heads-up. I was not much concerned with the subjective evaluation of the filters, but more with the objective data.
There is an obvious discrepancy between the Topping's filter mode numeration with associated impulse responses and Amir's measurements. Actually they only match in Filter 3, all other 6 filters are mismatched. I was just wondering if Amir could confirm his numbered filters impulse responses. If the accuracy is confirmed, which I assume it is, I would at least expect from Topping, for a unit selling for $500, to correct the filters order in their online manual.
 
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