Topping DM7 8-Channel DAC Review

[dartinbout]

There has been an expressed need for such an affordable MCH DAC for quite a while but, apparently, Topping/SMSL has only now seen good reason to market one. I had an extended email discussion with Topping/SMSL about an 8channel DAC and/or the possibility of clock-synching multiple stereo DACs about 3-4 years ago.

Thank you Kal and all the others who acted as the Yenta, because the progeny was delivered today

 

[Katji]

In a previous life I found myself implementing RBJ EQ filters for a pet project. I made the mistake of coding the biquad in 32-bit float (single precision) instead of 64-bit float. The numerical inaccuracy that resulted produced somewhat subtle, but audible issues. Most notably high-order distortion in bass tones, easily visible in measurements. Changing the code to use double precision solved the problem.

In general distortion introduced by digital filters is negligible, under the important condition that they are implemented correctly.

We had to change a lot of legacy MIS applications to 64-bit floats. i don't remember the details but problem became apparent, maybe it was when some users used to export the data and combine it in Excel.

 

[dartinbout]

Can we start an owners thread and just ban anybody who asks why their is no Amiga, DB25 or Parallel cable support.

 

[phoenixdogfan]

Is this diagram easier for your understanding?
View attachment 218940

I seem to remember this might have been covered before, but maybe not. Does it make any difference if Pin 3 is floated (disconnected) at the XLR connector or at the RCA plug? Seems to me if the former can be done, it would be a very simple matter to disassemble the XLR plug, and simply cut the wire connecting Pin 3. Save oneself the trouble of buying Benchmark or Emotive cable with the floated Pin 3.

 

[Katji]

Can we start an owners thread and just ban anybody who asks why their is no Amiga, DB25 or Parallel cable support.

Parallel printer cables, iirc, had to switch off PC before connecting the printer or it could blow the port.
And fiddling with serial comms port setups and conflicts, before USB.
Not "good old days."

Yeah, owners/users thread like that.

 

[Holmz]

That is not an answer to my question, nor related to your argument that you can calculate SINAD of an audio processing software.

Here was your question:

Is that done on audio processing software?

Here was my answer:

All a DAC does is convert numbers to signals.

But S/W either decodes 5.1, 7.n.n etc, or does bandpass filtering for a crossover, so something on that order.

Maybe you need to consider reasking the question in a way that makes it easier to for both parties to understand what the question is?


For an analogue signal we can compare the signal before and after we go through a box, a cable, or a whatever.
And we can do that by differencing the input and the output and integrating it into a something that measures, say, the RMS power.
For a digital representation of an analogue signal we can do that in the domain of numbers.
If it is one channel ofd digital becoming 2, 3 or 4 channels of digital we need need some model to know what should be happening.

How do you define distortion in a digital signal?

Usually it something like:
|(B-A)/A|

… where A is truth and B is the signal being measured.


Passband ripple is a good example.

• If we want ripple < -50 dB, then we can design a filter to achieve that.
• If we want ripple to be <-150 dB then we can do that, but it might not keep up in real-time.

Both can be measured to show that they hit their specs.
Both can distort to an extent.

 

[Kal Rubinson]

Thank you Kal and all the others who acted as the Yenta, because the progeny was delivered today

You beat me. Mine is due Wednesday.

 

[dartinbout]

You beat me. Mine is due Wednesday.

Music (more specifically surround) is my favorite remaining drug. I can quit everything else but this. Currently listening to Led Zeppelin II Quad Reel to Reel. Holy F_____ B_lls!

 

[sam_adams]

Thank you Kal and all the others who acted as the Yenta, because the progeny was delivered today

You beat me. Mine is due Wednesday.

Who will be brave enough to open it up and show us the insides?

 

[dartinbout]

These Topping devices are kind of a bitch to bust open. I popped open the DX7 Pro to play footsie with with the pre-amp op-amps. I had a conversation with Topping and, although they helped, the warranty vanished along with my op-amp innocence.

 

[da Choge]

Went out to a great Italian dinner tonight with a Negroni to start and then split a bottle of wine, so take my queries with appropriate skepticism. I know you more sophisticated multichannel guys have software programs on your enhanced Windows/Mac computers, and that software can redirect channel mapping appropriately. If I want to use the DM7 with all my multichannel files and basic ROON processing, how often do you think I will get inappropriate/inadequate channel mapping configurations? After all, this is just a basic 8-channel DAC with no added DSP abilities (except for native DSD [.dsf] conversion; and, BTW, does anybody know if this unit can process .dff files?).

I believe I've encountered reports where there has not been universal convention in channel-mapping schemes with multichannel music files . In fact, I just read of issues with this and the Okto Dac8 Pro. I know this is a very basic multichannel DAC (and kudos to Topping), but are we going to have to use high-powered PCs with appropriate operating systems & software (and not our ROCK NUCs) to get the best out of this component? Just an honest inquiry, 'cuz I really want to pull the trigger on this unit.

 

[phoenixdogfan]

You beat me. Mine is due Wednesday.

Now you'll have the Octo and this one. Don't you also own the Exasound?

 

[voodooless]

are we going to have to use high-powered PCs with appropriate software (and not our ROCK NUCs) to get the best out of this component? Just an honest inquiry, 'cuz I really want to pull the trigger on this unit.

How is a “high-powered PC” going to fix a channel mapping issue?

does anybody know if this unit can process .dff files?).

USB DACs don’t process files. They are giving streams of data that they can playback via the player software. It is responsible for parsing the dff file and extracting the audio streams for playback. Since the DAC supports direct DSD as well as DOP, a player supporting dff should be able to play the file via the DAC.

 

[da Choge]

a player supporting dff should be able to play the file via the DAC

That's great! Thank you.

It's not a "high-powered" PC, Sorry! -- it would be an appropriate software program, that a PC with the appropriate OS could be able to run. I have a ROCK NUC and I store and run all my music files through that; I was wondering if there would be problems with channel-mapping with the ROCK OS and the DM7. If I am misunderstanding this process, please correct me.

 

[dartinbout]

Went out to a great Italian dinner tonight with a Negroni to start and then split a bottle of wine, so take my queries with appropriate skepticism. I know you more sophisticated multichannel guys have software programs on your enhanced Windows/Mac computers, and that software can redirect channel mapping appropriately. If I want to use the DM7 with all my multichannel files and basic ROON processing, how often do you think I will get inappropriate/inadequate channel mapping configurations? After all, this is just a basic 8-channel DAC with no added DSP abilities (except for native DSD [.dsf] conversion; and, BTW, does anybody know if this unit can process .dff files?).

I believe I've encountered reports where there has not been universal convention in channel-mapping schemes with multichannel music files . In fact, I just read of issues with this and the Okto Dac8 Pro. I know this is a very basic multichannel DAC (and kudos to Topping), but are we going to have to use high-powered PCs with appropriate operating systems & software (and not our ROCK NUCs) to get the best out of this component? Just an honest inquiry, 'cuz I really want to pull the trigger on this unit.

I only know of one major release where the channel mapping failed. Cassandra Wilson's Traveling Miles DVDA. I have over 250 MC albums and, at least in my collection, it's not an issue. I use J. River and the asio plays DSF and DFF MC files. Can you send me a link to the Okto thread that mentioned the mapping failure? I fixed the Wilson album but not in J. River.

 

[da Choge]

I only know of one major release where the channel mapping failed. Cassandra Wilson's Traveling Miles DVDA. I have over 250 MC albums and, at least in my collection, it's not an issue. I use J. River and the asio plays DSF and DFF MC files. Can you send me a link to the Okto thread that mentioned the mapping failure? I fixed the Wilson album but not in J. River.

Thank you! - exactly the kind of reassurance I was looking for. Can't remember exactly where I read of this (Okto issue), but I think it was just yesterday. I believe it was in response to one of Kal's posts on another site [maybe a UK site?]. It's a little late tonight; I'll search for it tomorrow.

 

[ClassicalDJ]

Thank you! - exactly the kind of reassurance I was looking for. Can't remember exactly where I read of this (Okto issue), but I think it was just yesterday. I believe it was in response to one of Kal's posts on another site [maybe a UK site?]. It's a little late tonight; I'll search for it tomorrow.

You could be referring to a Roon DSP (Procedural EQ mix) issue when running crossovers for 5.0 files. I’ve experienced this with HDMI so I’m not sure if it’s an issue for USB DACs. Still have some channel mapping hacks that I will attempt to fix, but I’m hoping not to have to switch between DSP settings for 5.0 and 5.1 files.

Some Roon users may desire different or more sophisticated DSP from something like JRiver, CamillaDSP, or Dirac Live, which I believe would require having those softwares running on a Roon core (or endpoint?) in the listening room (Windows or MacOS machine in the Dirac Live case), and the final sampling rate options may be limited.

 

[dualazmak]

I seem to remember this might have been covered before, but maybe not. Does it make any difference if Pin 3 is floated (disconnected) at the XLR connector or at the RCA plug? Seems to me if the former can be done, it would be a very simple matter to disassemble the XLR plug, and simply cut the wire connecting Pin 3. Save oneself the trouble of buying Benchmark or Emotive cable with the floated Pin 3.

Hello @phoenixdogfan,

You are right!

My posts #627 and #655 are intending to share reasonably-priced, widely commercially available, safe, easy-to-be-understood option(s) of TRS(balanced)-to-RCA(unbalanced) conversion for rather naive beginner people who would hate/hesitate doing any DIY work on cables and plugs.

(BTW, as you may understand, at least now and for a while, I have no intention at all of using TOPPIG DM7 since I already have OKTO DAC8PRO.)

 

[sseppala]

Does anyone know where the preamp mode volume defaults to and does it retain the set volume after complete power loss?

I asked this from Topping and this is their reply.

Yes，the volume setting is saved under that situation, the default volume is -30dB.

I would still appreciate if some dm7 owner could verify this. Personally I would have preferred the default volume to be even lower, -40dB for example, but I quess -30dB is OK.

 

[dartinbout]

I can confirm the default is -30db through boot, power loss and reset (more on why I had to reset the unit later).