[kiwikaki]

Hello, I have the mdac from about 1 week, with the stereo I noticed a nice improvement in the sound and I am satisfied, however with the denon d2000 connected to the headphone output of the mdac, I notice a thicker sound, silky and harmonic rich, but compared to the simple  headphone pc (win 7 64) in many songs, especially classical music, known several distortions, drivers dellla headphones seem holes. (In steps orchestral dynamic, I need to keep the volume to below about -15/-20 db, because the sound distorts).
I have version 0.99 of the firmware, mdac connected with usb to pc, player foobar (with both set out with that WASAPI with asio4all and also smooth out).
You have any recommendations? Why so the denon are unheard.
Sorry for the English translated with google.

 

[aivar1988]

Im interested in this M-DAC but as i understand it has bad volume control technology? i dont have volume control on my amp. my setup is like this: HP compaq -> DAC -> AMP -> speakers . so i guess ill be better of with lavry for example ?
 
 
Quote:

 

This DAC's built-in volume control attenuates the signal in the digital domain by scaling the digital signal.  Full volume (i.e. zero dB) should retain full resolution.  The more you attenuate the signal the more resolution is lost.  Small amounts are OK, but a point is reached where the signal will become noticeably distorted.  This is due to the reduced "bit resolution" by the digital scaling.  This DAC uses an internal resolution of 32 bits, so attenuating by -48dB would reduce it to about 24 bits, but every -6dB loses another bit (approximately)of resolution and also drives the analog output closer to the noise floor.
The worst case scenario would be using heaps of digital attenuation to counter an excess of gain in, say, the amplifier.  The signal would first be attenuated (and distorted) too much at the DAC outputs, then all that noise and distortion would be magnified by the high-gain amplifier.  This shows up the importance of correct matching of components in the audio chain, as well as matching signal levels for best performance. 
If you are using this DAC as a "one-box solution" for headphone listening (i.e. DAC and amp) and you have particularly sensitive headphones, then you may find that you have to use too much digital attenuation all the time.
As I understand it, you can configure this DAC to operate at full output levels (like a normal DAC) without using it's digital attenuator.  This could then be fed into a normal amplifier which has an analogue attenuator (volume control) that may give a more balanced solution (YMMV).  It is good that you have the option to use it either way, so you can discover what works best for you.
 

 
anyone has compared m-dac with lavry da11 or benchmark dac1 ?
 

 

[danofdanger]

The attenuation is done at the digital level yes but is done in a way that is actually better in my opinion than that of analogue attenuation. 
 
This is what is thought by most and i did at the beginning as well..
 
"If 1 bit is lost for every 6db then at -24db 4 bits is lost from the 32 bit dac, at -48db 8 bits is lost and finally at -78 a total of 13 bits is lost leaving 19 bits out of the 32 bit dac.
Now for people who use 24 bit content they will loose resolution but for people using only 16 bit will still be fine using the digital volume well below -40db."
 
This sounds however to be a great thing and that even reducing it all the way down to -80 would result in no resolution lost with 16 bit and very slightly with 24 bit, however the actual result is not this and i will explain why.
 
With analogue attenuation the "entire" signal is reduced via the variable resistor including the noise presented by the source signal, with digital attenuation however because the volume is done at the digital level the noise is unaffected because the noise is present still after the dac which is normal. So when digital attenuation is done the signal to noise ratio is reduced in parallel, so the more the volume is reduced the more the SnR is decreased with it. This however is rectified with something called DSD which moves the error outside the audible frequency range and removes this artifact but reduces the possible range of digital attenuation. The range recommended is between 0 and -40, if you go below that then it is a concern that you may get a reduction in audio quality. This is also rectified by using properly matched systems with making sure the amplifier in the chain is not too sensitive to input voltage or inserting inline attenuation or preamps with analogue volume controls.

 

[MoonUnit]

Quote:

The attenuation is done at the digital level yes but is done in a way that is actually better in my opinion than that of analogue attenuation. 
 
This is what is thought by most and i did at the beginning as well..
 
"If 1 bit is lost for every 6db then at -24db 4 bits is lost from the 32 bit dac, at -48db 8 bits is lost and finally at -78 a total of 13 bits is lost leaving 19 bits out of the 32 bit dac.
Now for people who use 24 bit content they will loose resolution but for people using only 16 bit will still be fine using the digital volume well below -40db."
 
This sounds however to be a great thing and that even reducing it all the way down to -80 would result in no resolution lost with 16 bit and very slightly with 24 bit...

 
This is not right. It's theoretically correct for an ideal DAC with perfect 24 bit resolution, but for a practical device like the M-DAC, you have to work from 0dB and consider what the device's actual resolution is, because digital attenuation throws away the high order bits first, not the low order bits. 
 
At full scale, the M-DAC has 0.002% THD+N, which means the noise and distortion floor is at -94dB, regardless of the resolution of the input signal. When you digitally attenuate by 40dB, you're producing a device whose noise and distortion floor is now at only -54dB. This is in the realm of low quality tube amp territory, and will be definitely audible.

 

[danofdanger]

My above statement should be correct, it was quoted from the person who made the m-dac in the first place, i first thought that resolution would be lost due to bits being thrown away but he said this is not the case due to noise shaping, which is a feature done by dsd.

 

[TokenGesture]

Got a question - is there an improvement in SQ using the XLR out over RCA?

 

[TheGrumpyOldMan]

Quote:

Got a question - is there an improvement in SQ using the XLR out over RCA?

Straight from the manufacturer:
 

Output voltage	RCA: 2.25V RMS;  XLR: 4.5V RMS
Total Harmonic Distortion	RCA: <0.002%;  XLR: <0.0008%
Dynamic range	RCA: >115dB;  XLR: >122dB
Crosstalk	RCA: <-120dB;  XLR: <-130dB

 
So you get a stronger, cleaner signal. Whether that will improve actual sound quality depends entirely on the rest of your chain (source, amplification and most importantly headphones)
 
In my case, the practical necessity was that the balanced amp I'm using -requires- a balanced input to deliver its output potential (in electrical design terms, not just subjective listening)

 

[TokenGesture]

Thanks!

 

[hduong]

 
Just received my MCRU M-DAC External Linear Power Supply.  No real impression just yet as I have not gotten a chance to A/B between the stock one.  Seems to have increased clarity.  Especially in the treble region.

 

[daniel_hokkaido]

hey 
 
will be super curious to see your impressions! I got rca noise stoppers recently and that also helped clear up the soundstage a tad. I'm a big believer in good power cables
and power in general. If we could get some MDAC + this external psu comparisons to other more expensive DACs then that would be amazing too. Although that is an ideal!

 

[aphinity]

what's the best way to connect the MDAC to a MacBook Pro?  an USB to SPDIF converter?  optical?  how would i keep the signal balanced?  thx.

 

[daniel_hokkaido]

id go with plain usb ..but get a decent usb cable. e.g furutech formula 2. as usb input is asynchronous. I find it smoother and more engaging than optical in. 
 
re: balanced...what do you mean? 

 

[TheGrumpyOldMan]

I have used both and use either based on practical considerations. When using my Macbook further away from the M-DAC, I found longer optical cables to be easier to use in terms of length and stiffness than a corresponding USB cable. But when stationed next to each other, I'm using a very short USB cable.
 
USB has the distinct benefit of letting the M-DAC and Macbook talk to each other, so if you adjust the volume (or mute) on either, it well tell the other, i.e. the Macbook volume controls will adjust the M-DAC's digital volume (presumably a better implementation than the MB's internal one) and vice-versa, using for example the M-DAC's remote control, it will tell the Macbook the adjusted volume level or that it's muted. This feature is optional and can be enabled/disabled in the menu.
 
Sound quality: Won't go into how the correct transmission of 0s and 1s is supposed to turn into different sound if they're transmitted via a different (decent) cable. Though related: one of the many nice features the M-DAC has is the built-in BitPerfect test to at least verify the basic correct transmission of the digital audio data in the correct frequency & bit-depth (via either input). If you want to explore whether that means it is still potentially not "perfect", the PFM forum(s) have had many a lively discussion on that and everything else M-DAC.
 
As far as "balanced" goes: that is entirely in the analog domain, and the M-DAC takes care of setting up the correct signal to the RCA and/or XLR connectors. There is no differentiation in the digital domain, i.e. your source stream.
 
Personally, I've been using both types of connection and couldn't hear a difference. One thing I really wouldn't bother with is the type of converter you mention since BOTH the M-DAC and the Macbook can handle EITHER type of connection anyway. More importantly: just make sure that IF you have high-def tracks, you use something like BitPerfect (unrelated to the M-DAC's test) to switch to the corresponding settings, or a dedicated player that does that, if you prefer.

 

[daniel_hokkaido]

if using mac os x ...id say audirvana is a great player option. It has 15 day free trial also. v1.5 should be out soon and finally will have option for plugins e.g High End EQs etc 
 
@hduong...still waiting with great interest on your impressions of Mdac with new PSU.   

 

[TokenGesture]

Quote:

if using mac os x ...id say audirvana is a great player option. It has 15 day free trial also. v1.5 should be out soon and finally will have option for plugins e.g High End EQs etc 
 
@hduong...still waiting with great interest on your impressions of Mdac with new PSU.   

Hey - thanks for this recommendation. I just downloaded the trial version, and the improvement over itunes is immediately noticeable. I'll definitely buy it!