Topping DM7 8-Channel DAC Review

[mgbpuff]

From the tenor of the last several posts, this "inquiry" may not receive a lot of love, but my interest in the Topping DM7 is to use it as a DAC for multi-channel music fed by the USB output of a streamer which transmits 5.1 or 7.1 multichannel music files from a Roon ROCK NUC; NOT as a part of a Home Theater AVR. The main FR and FL channels would be amplified by a balanced stereo amp fed from the first two channels of the DM7. I would like to feed the the remaining channels back into the single-ended RCA 7.1 multichannel inputs of my AVR and use its amplification for these surround channels.

Because of what John Yang has posted, I think I would not want to use modified TRS to RCA cables (ones which would float the negative line). However, I would consider using balanced-to-unbalanced transformers (two higher quality units are denoted below from RDL). I know this would degrade the signal of the surround channel signals somewhat, but as they are just the surround channels, they are less of a concern than the main two front stereo channels. And for stereo music listening, I still get all the goodness of the balanced high-quality DM7 DAC.

These are the units I would consider:
View attachment 221153
RDL TX-AFC1F
View attachment 221154
RDL FP-BUC2

The FP-BUC2 has better specs than the TX-AFC1F, but it is also a line amplifier, which could come in handy in balancing the signal strengths of the surround channels with respect to the main balanced stereo line. I would obviously need 2 to 3 of the second unit to accomplish what I want.

I'm asking the more knowledgeable (than me) members of the forum as to what they think of this scheme, audio-wise? -- sound or unsound

This is the best post yet for a practical way to use the DM7, everything else has been by computer / DIY esoterics. Here is an 8 channel bal to unbal converter that only cost $369. Never used it myself, but it looks like a good fit. http://www.sonicimagerylabs.com/products/Model898B.html

 

[dualazmak]

From the tenor of the last several posts, this "inquiry" may not receive a lot of love, but my interest in the Topping DM7 is to use it as a DAC for multi-channel music fed by the USB output of a streamer which transmits 5.1 or 7.1 multichannel music files from a Roon ROCK NUC; NOT as a part of a Home Theater AVR. The main FR and FL channels would be amplified by a balanced stereo amp fed from the first two channels of the DM7. I would like to feed the the remaining channels back into the single-ended RCA 7.1 multichannel inputs of my AVR and use its amplification for these surround channels.

Because of what John Yang has posted, I think I would not want to use modified TRS to RCA cables (ones which would float the negative line). However, I would consider using balanced-to-unbalanced transformers (two higher quality units are denoted below from RDL). I know this would degrade the signal of the surround channel signals somewhat, but as they are just the surround channels, they are less of a concern than the main two front stereo channels. And for stereo music listening, I still get all the goodness of the balanced high-quality DM7 DAC.

These are the units I would consider:
View attachment 221153
RDL TX-AFC1F
View attachment 221154
RDL FP-BUC2

The FP-BUC2 has better specs than the TX-AFC1F, but it is also a line amplifier, which could come in handy in balancing the signal strengths of the surround channels with respect to the main balanced stereo line. I would obviously need 2 to 3 of the second unit to accomplish what I want.

I'm asking the more knowledgeable (than me) members of the forum as to what they think of this scheme, audio-wise? -- sound or unsound

Just wondering with a bit of confusion. In the Datasheet for RDF FP-BUC2, we can find; "This module features two identical active (transformerless) channels." Then, what would be the internal active circuit for bal-to-unbal conversion? I could not find the detailed circuit diagrams...

Never used it myself, but it looks like a good fit. http://www.sonicimagerylabs.com/products/Model898B.html

For this bal-to-unbal and unbal-to-bal bidirectional converter, we can find the circuit diagram in the Specification PDF;

The selectable grounding mode for pin-1 and XLR outer shield , i.e., (1) to be open/floated, (2) to AGND, (3) to chassis GND, would be nice if we would have ground-loop and/or any other grounding noise issues by using this converter; we may test three (or 3 x 3 =9, so nine?) grounding modes for possible elimination of the noise issue.

The possible deteriorations (or not) in sound quality would depends on the PRECISION DIFFERENTIAL -6dB LINE RECEIVER chip and the LINE DRIVER -5.8dB chip, I assume.


I hope, if possible, amirm or any other people would review, measure and evaluate these bal-to-unbal converters.

 

[Johannesthalos]

Please @JohnYang1997 will there be a "DM5" with less outputs for a smaller prize?

 

[da Choge]

Here is an 8 channel bal to unbal converter that only cost $369. Never used it myself, but it looks like a good fit. http://www.sonicimagerylabs.com/products/Model898B.html

Mgbpuff - thanks for bringing this to our attention. I've seen similar units from Tascam, etc., but this one looks really nice and has excellent published audio performance specs. I'm interested in it, but have some concerns.

Don't want to get too much off topic here, but the datasheet for the Sonic Imagery converter states: "The following diagram is a simplified block diagram of the 898B. It should be noted that the analog audio path is DC coupled from input to output. No interstage capacitors are used in the design. This feature allows the 898B to act like a “straight wire.” Hence the units bandwidth extends to and is flat to DC. This is important for data acquisition, seismological and scientific research." Its User Manual further goes on to say something like, components with higher DC offsets at the outputs should not be used with their converter without some kind of correction.

This has me a little concerned because we know the DC offset of the Topping D10B measures around 60mV and shouldn't be used with an unbalanced output. John Yang has stated that he thinks the DC offset of the DM7 is "smaller than the D10 Balanced". And, although he recommends against it, he says that if one intends to use the DM7 with an unbalanced output, the next stage should have some kind of DC blocking. Is there some way to counteract DC offset currents that would be passed through a converter like the Sonic Imagery 898B without compromising what appear to be its excellent specs/measurements (short of wiring a capacitor into the circuit)? I don't think you'd have the same issues with a passive transformer-based balanced-to-unbalanced converter, but they generally have much lower audio performance ratings.

 

[DWPress]

I would suggest anyone trying to use this with unbalanced connections go with one of the cheap PC sound cards like Asus, Creative, etc (if you're on PC) until you move up to balanced amps. John Yang and other people have repeatedly chimed in advising against or offering $$ solutions.

By the time you get the converter(s) and cables you might actually save some money.

 

[MCH]

I would suggest anyone trying to use this with unbalanced connections go with one of the cheap PC sound cards like Asus, Creative, etc (if you're on PC) until you move up to balanced amps. John Yang and other people have repeatedly chimed in advising against or offering $$ solutions.

By the time you get the converter(s) and cables you might actually save some money.

Well, if they had remote control and display....

I think many people would like to be able to use this with balanced and umbalanced amps they already have. It would be great to be able to take profit of balanced connections to the balanced amps and still be able to use the unbalanced ones as well.
If it was a design decision of topping, it was an unfortunate one in my opinion.

 

[mgbpuff]

Mgbpuff - thanks for bringing this to our attention. I've seen similar units from Tascam, etc., but this one looks really nice and has excellent published audio performance specs. I'm interested in it, but have some concerns.

Don't want to get too much off topic here, but the datasheet for the Sonic Imagery converter states: "The following diagram is a simplified block diagram of the 898B. It should be noted that the analog audio path is DC coupled from input to output. No interstage capacitors are used in the design. This feature allows the 898B to act like a “straight wire.” Hence the units bandwidth extends to and is flat to DC. This is important for data acquisition, seismological and scientific research." Its User Manual further goes on to say something like, components with higher DC offsets at the outputs should not be used with their converter without some kind of correction.

This has me a little concerned because we know the DC offset of the Topping D10B measures around 60mV and shouldn't be used with an unbalanced output. John Yang has stated that he thinks the DC offset of the DM7 is "smaller than the D10 Balanced". And, although he recommends against it, he says that if one intends to use the DM7 with an unbalanced output, the next stage should have some kind of DC blocking. Is there some way to counteract DC offset currents that would be passed through a converter like the Sonic Imagery 898B without compromising what appear to be its excellent specs/measurements (short of wiring a capacitor into the circuit)? I don't think you'd have the same issues with a passive transformer-based balanced-to-unbalanced converter, but they generally have much lower audio performance ratings.

I assumed we are looking for a balanced to unbalanced conversion. The 898B in this case is presenting a balanced input to the balanced output of the DM7, so DC offset is not a problem there. The unbalanced output of the 898B is stated to have a DC offset into a 10Kohm resistive load of less than +/-1mV. If you need real assurance, you should contact the manufacturer.

 

[da Choge]

The 898B in this case is presenting a balanced input to the balanced output of the DM7, so DC offset is not a problem there.

I think that's probably correct; I guess there would be no DC offset of a balanced output from the DM7, so therefore not a concern. Don't know why I didn't catch this originally. Thanks!

I don't think my plans have anything to do with being able to "move up to" (afford) balanced amps. They are aimed rather at not having two entirely separate systems. I can have a separate balanced analog preamp/amp stereo system for music listening which can be used in conjunction with my AVR (with the preamp having Home Theater Bypass). But I don't really want to have an entirely separate system with separate controls, etc., for including the surround channels (in addition to the front stereo channels which do utilize a balanced amp) when listening to my multichannel music files. I believe a unit like the Sonic Imagery 898B and the Topping DM7 would allow that. An AV processor with balanced preamp outputs might be another consideration, but I don't think there are any with balanced 7.1 multichannel inputs.

 

[dualazmak]

I believe a unit like the Sonic Imagery 898B and the Topping DM7 would allow that. An AV processor with balanced preamp outputs might be another consideration, but I don't think there are any with balanced 7.1 multichannel inputs.

Not an "AV" processor, but Yamaha MX-A5200 is full balanced input 11-Ch (Class AB) multichannel amplifier which can be used for up to 11-Ch balanced-input amplification in AV setup, I believe.
https://usa.yamaha.com/products/audio_visual/av_receivers_amps/mx-a5200_u/index.html
https://www.audioholics.com/av-preamp-processor-reviews/yamaha-cx-a5200-mx-a5200/conclusion
https://www.phileweb.com/news/d-av/201809/05/44960.html

As shared here, here and here,I intensively tested and evaluated Yamaha MX-A5200 in my multichannel multi-driver multi-way multi-amplifier stereo audio (not AV) project and, at least in my project, I decided not to use it, though.

That was the start of my long and intensive amplifier exploration journey in my project. You would please find summary of my such journey here on my project thread.

 

[Hemi-Demon]

@JohnYang1997

Does the DM7 have MQA, or was it excluded in this particular model? Sometimes I use Tidal, and wouldn't mind if it was included.

 

[Music1969]

@JohnYang1997

Does the DM7 have MQA, or was it excluded in this particular model? Sometimes I use Tidal, and wouldn't mind if it was included.

All Topping DACs that support MQA decoding have it on their product page.

Have you looked at DM7 product page?

DM7 8CH USB DAC-TOPPING

 

[amazingtazing]

Hi all, will this DAC work for something like this?

I have 2 JBL studio monitors and a monoprice monolith subwoofer. Currently I'm using the redundant RCA ports on my Motu M4 and the internal crossover to drive the sub, to create some sort of a crap 2.1 setup.

Now since my subwoofer has a balanced input, could I set up this DAC as a 5.1 system in Windows, hook up the 3rd channel to the subwoofer, then using equalizer apo lowpass the left and right inputs into a separate channel and assign it to the subwoofer? Is this possible?

 

[mdsimon2]

I just did a bit of research on this and it looks like there are many reasonably priced used Dolby 5.1 decoders. Look up the DP562 for example, here is one for $40 on eBay -> https://www.ebay.com/itm/165353343476?hash=item267fd3c9f4:g:hH4AAOSwr61iFv8B.

Michael

I ended up buying this to try it out as it was so cheap, so far seems to work great with Netflix sending DD5.1 from an old AppleTV optical output (optical -> optical to SPDIF converter -> SPDIF to AES transformer). At this point I've only tested the individual AES outputs but still want to get a miniDSP U-DIO8 to try my hand at a DIY AVR (DD5.1 -> Dolby DP562 -> miniDSP U-DIO8 -> RPi4 / CamillaDSP -> multichannel DAC).

Michael

 

[Haruko]

7.1 is ok but hdmi and 2 more channels for 7.1.2 for atmos would be killer and most prob. end game for some

 

[Kal Rubinson]

7.1 is ok but hdmi and 2 more channels for 7.1.2 for atmos would be killer and most prob. end game for some

5.1.2 is an alternative.

 

[Jimster480]

I ended up buying this to try it out as it was so cheap, so far seems to work great with Netflix sending DD5.1 from an old AppleTV optical output (optical -> optical to SPDIF converter -> SPDIF to AES transformer). At this point I've only tested the individual AES outputs but still want to get a miniDSP U-DIO8 to try my hand at a DIY AVR (DD5.1 -> Dolby DP562 -> miniDSP U-DIO8 -> RPi4 / CamillaDSP -> multichannel DAC).

Michael

That is quite a few links in the chain to use this. I hope they make a other one with optical, coax, maybe aes and also with mqa support for tidal.

 

[gandalfandula]

while i appreciate the great engineering in what they have provided, the single USB input is useless to me. my signal path needs SPDIF or some other paired 2 channel inputs coming in from my DSP for my multi-way stereo speaker setup. as it stands this can really only be used with a computer setup, which isn’t my preference for hifi use. tragically close to perfection!

 

[JohnYang1997]

A new firmware supporting independent channel volume control is coming.

 

[Sokel]

A new firmware supporting independent channel volume control is coming.

That's really good news!

 

[dartinbout]

Holy F___Nutz!
I asked and Topping did it! I Lub dis company!

"Dear Topping

I believe that the chipset is capable of allowing individual channel volume alteration. Is there any plans to update the firmware to allow this functionality?

service <[email protected]>​	Thu, Jul 28, 12:23 AM (6 days ago)

Hi,

I will send your feedback to the R&D department.

Best Regards

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TOPPING SERVICE