Topping DX7 Pro DAC and Headphone Amp Reviewed

[NielsMayer]

i'm surprised nobody's made a self-powered "USB stick" that just plugs into an HDMI-shaped IIS-LVDS "port" on a DAC and has a USB type-B, microUSB, or USB-C port on the other end. Bonus of shortest length (0) IIS-LVDS cabling.

Of course, if that became any good, why even have a USB interface on the DAC? Make cheaper DACs that just work doing one thing well, and worry less about USB-induced noise by keeping all that encapsulated as best possible in the separate metal box encapsulating the USB->IIS-LVDS "stick".

 

[evrial]

Does LVDS has any confirmed measurable advantage?

 

[ZeDestructor]

Does LVDS has any confirmed measurable advantage?

1. It's I²S/I2S/IIS, not LVDS. LVDS is just a general decription of the signal type (namely a differential signal, at low-voltage). Fun fact, USB, HDMI, PCIe are also all LVDS signals, amongst many.
2. Based on numbers measured by amir here, there is no meaningful difference, so just use USB directly. The only people who should be caring about passing around I²S directly are the few people who are looking at hacking up an AVR/AVP and feeding that into 7 stereo DACs.

 

[NielsMayer]

Does LVDS has any confirmed measurable advantage?

It has all the advantages of any balanced signalling system. In particular, noise rejection, and less radiation from clock and serial signals operating at very high frequencies. At radio frequencies, each "wire" is best described as "antenna".. In other words non-balanced wires, even on a circuit board radiate noise, whereas pairs of balanced LVDS signals can be routed to the multiple devices needing them and attempt to "contain" the radiation. You might see them running in pairs isolated by some distance of "ground plane" on a circuit board.

"As long as there is tight electric- and magnetic-field coupling between the two wires, LVDS reduces the generation of electromagnetic noise. This noise reduction is due to the equal and opposite current flow in the two wires creating equal and opposite electromagnetic fields that tend to cancel each other. In addition, the tightly coupled transmission wires will reduce susceptibility to electromagnetic noise interference because the noise will equally affect each wire and appear as a common-mode noise. The LVDS receiver is unaffected by common mode noise because it senses the differential voltage, which is not affected by common mode voltage changes."

https://en.wikipedia.org/wiki/Low-voltage_differential_signaling

 

[Alou]

LVDS never really caught up regardeless of benefits or not,its rear to find on devices and completely non existant in the Pro Audio world , i am working in the Broadcast & film Industry and found about it from Fan or Hobby audio fan forums.

 

[pacman]

I'll buy a Shure SRH1540, with impedance of 45 Ω. It'll be a problem pairing it with the DX7 Pro?

 

[Alou]

I think they will be fine ,at 45ohms basically they dont need an amp but it will improve the sound clarity.

 

[ZeDestructor]

LVDS I²S never really caught up regardeless of benefits or not,its rear to find on devices and completely non existant in the Pro Audio world , i am working in the Broadcast & film Industry and found about it from Fan or Hobby audio fan forums.

I²S never caught on in pro audio because S/PDIF and/or AES3/EBU are already there and working well as a digital interconnect. I²S, in comparison, is a chip-to-chip interconnect designed to connect your DAC or ADC to your digital sound source (chipset, sound card DSP chip, some random XMOS-somenumber, an S/PDIF reciever, etc) - it's just not meant to interconnect seperate pieces of hardware in the first place.

That's why I said earlier the only people who should care about I²S IO on DACs are the hackers who are planning to hack up an AVR/AVP and rip the I²S signals between the DSP chip and the DAC chips in the AVR/AVP.

@NielsMayer the context here would suggest that the guy is asking about I²S-LVDS connections vs USB or S/PDIF, not LVDS itself. I could be wrong though, and you wrote a nice explanation or CMRR anyways.

 

[NielsMayer]

LVDS never really caught up regardeless of benefits or not,its rear to find on devices and completely non existant in the Pro Audio world , i am working in the Broadcast & film Industry and found about it from Fan or Hobby audio fan forums.

LVDS never caught on, as in SCSI, Firewire, SATA... uhuh.....

 

[NielsMayer]

looks like 11/11 sales have the dx7pro down to $515.99

 

[pacman]

looks like 11/11 sales have the dx7pro down to $515.99

Bought it for $514 on Shenzhenaudio Store

 

[Evgeniy]

High frequency tones do generate ultrasonic tones which thankfully we don't hear but impacts THD+N versus frequency:

Very strange, high level of distortion on 10-20 kHz.
It's only on 48 kHz rate or at 44 / 88 / 192 too ?

Amirm, can you provide spectre of these distortions on 10/20 kHz signal at 44 & 48 kHz ?

 

[digicidal]

Bought it for $514 on Shenzhenaudio Store

I picked up one as well. Still waffling on what to do in my main system (new prepro vs. separates for everything) so with the sale figured this is a relatively cheap way to fulfill some upgraditis without dropping major coin on something else. Not that I expect to hear much improvement, if any, over my DacMagic v1 (despite measuring far, far better) - but getting rid of my passive pot controller and adding in BT for my other PC seemed like a nice bonus.

 

[greeny]

How is this compare with the Schiit Asgard 3?

 

[digicidal]

How is this compare with the Schiit Asgard 3?

I presume you're asking about the headphone section? On the DAC side it would depend on the module... but with the AK4490 it would likely be audibly indistinguishable... but that would depend highly on the implementation. This one almost assuredly measures better as a DAC - but unless they screwed something up, the Schiit is probably fine in that regard as well.

On the headphone side however, the Asgard has quite a bit more output and a decently lower output impedence... so if you're looking primarily for a headphone amp... it probably has a slight advantage. It really comes down more to the fact that the Topping is far, far more feature-rich and a provably excellent DAC implentation... but is $200 more (even on sale) - so you'd have to figure out where your priorities are on that.

 

[ramzi]

Heya people, so my DX7 Pro just got here as an upgrade to my trusty D50.

I have it configured like this atm, connected to an integrated amp:
AUTO (OFF), Output (LO), LO Mode (DAC), Line Out (RCA), BT (OFF), PCM FIR (MODE5)

I seem to have an issue with OPT, it's configured as OPT->RCA (DAC mode), but when playing some video content on the TV (OPT source), I get dropouts where the display shows ---kHz and then comes back with 48kHz, like it lost connection for a second or something...
I never had that issue with the D50.

Just wondering if anyone else using OPT saw dropouts like that?

 

[Alou]

Hi is the sound on the video ac3 or DTS because if thats the case i dont think it can decode it .

 

[ramzi]

Hi Alou, thanks for the quick reply, the format isn't the issue as the TV decodes it and uses PCM for the digital sound out (OPT), like I said that setup worked without any issues with the D50 for quite some time, and I had several dropouts with the DX7 in a 5 minute musical scene...

I've now completely powered it off and will let it rest a bit as I'm not sure if I fully powered it down after configuring, just used standby.

And just for comparison, using USB with Roon there don't seem to be any issues (yet), even hit it with some DSD512 upsampling.

 

[Alou]

its a strange behavior ,i would just flip through all the settings in the DX7pro menu just in case something was missed.
I am getting mine setup today it just arrived via post.

 

[Alou]

4.4mm

Never saw headphones with such a jack !