[spkrs01]

  To be honest I am not convinced a "superior"  DAC should need an expensive USB converter to sound at its best. Most comments suggest the digital inputs on the Metrum are poorly designed.

 
I think you need a usb/spdif converter, with the Octave purely because it does not have a usb input. Then to really get the best out of this Dac you need to up-sample from your music player. 
 
Even something relatively cheap like the HiFace 2, second-hand, with the right driver will improve the Octave sonically throughout the spectrum.....In your situation I would take this route rather than use a transport.
 
It really not too good an idea to go Dac to Dac....................

 

[complin]

They have a totally different approach to conversion and architecture irrespective of the circuit boards
 
Yes objective criteria are fine to weed out any potential issues or deficiencies (all products are a compromise!) but in the end its how it performs in a setup
 
Quote:

  I  would be curious to know what are those objective criteria you use to decide the  Metrum is a superior DAC compared to the MDAC.
Looking briefly at the circuit board and overall quality of both, some people might not share your view about which one is superior.

 

[Sapientiam]

  I  would be curious to know what are those objective criteria you use to decide the  Metrum is a superior DAC compared to the MDAC.
Looking briefly at the circuit board and overall quality of both, some people might not share your view about which one is superior.

 
Hard to answer this question without getting into fairly arcane technical details but I'll have a go.
 
The MDAC is using ESS9018 which is a sigma-delta based chip using noise-shaping to get the figures looking good. Noise shaping has various technical issues associated with it, many of which ESS have solved (compared to the other players in the field like ADI, TI/BB) but clearly not all. In particular the chip still exhibits shifts in the noise floor at particular output levels. Its also very hard to get enough subjective dynamics out due to the extremely high switching frequencies used in the on-chip DAC.
 
Metrum uses a ladder-type DAC and runs it at the lowest frequency (assuming you don't use your computer to oversample). Thus dynamics will tend to be better, also timbral accuracy. However the measurements relative to any ESS-based converter will suck - THD+N in particular and the FR will droop due to the NOS intrinsic roll-off.
 
Incidentally you're right there's something adrift with the Metrum's digital input - the digital ground beyond the isolation trafo goes into the ground fill.This induces HF noise currents into the sensitive analog ground and is a very common issue with commercial DACs, akin to the 'pin1 problem' with professional XLR connected kit. For anyone with the guts to mod, this can be quite simply fixed up. Just re-route the 0V side of the S/PDIF input with a dedicated ground wire back to the PSU input.

 

[complin]

In spite of these design compromises i've found it preferable to other DAC's costing 4 or 5 times the price.
I can perceive no roll off of high frequencies, its all there just not in your face presentation like much of todays digital reproduction.
Great dynamics and timbral accuracy, very very musical if you are into music rather that HI-FI 

.
 
Yes it has its limitations in terms of input capability and lack of native USB, handling very high rez files and DSD, but if you can live with this then its a real gem IMHO. 
 
Quote:

   
Hard to answer this question without getting into fairly arcane technical details but I'll have a go.
 
The MDAC is using ESS9018 which is a sigma-delta based chip using noise-shaping to get the figures looking good. Noise shaping has various technical issues associated with it, many of which ESS have solved (compared to the other players in the field like ADI, TI/BB) but clearly not all. In particular the chip still exhibits shifts in the noise floor at particular output levels. Its also very hard to get enough subjective dynamics out due to the extremely high switching frequencies used in the on-chip DAC.
 
Metrum uses a ladder-type DAC and runs it at the lowest frequency (assuming you don't use your computer to oversample). Thus dynamics will tend to be better, also timbral accuracy. However the measurements relative to any ESS-based converter will suck - THD+N in particular and the FR will droop due to the NOS intrinsic roll-off.
 
Incidentally you're right there's something adrift with the Metrum's digital input - the digital ground beyond the isolation trafo goes into the ground fill.This induces HF noise currents into the sensitive analog ground and is a very common issue with commercial DACs, akin to the 'pin1 problem' with professional XLR connected kit. For anyone with the guts to mod, this can be quite simply fixed up. Just re-route the 0V side of the S/PDIF input with a dedicated ground wire back to the PSU input.

 

[Sapientiam]

Interesting read, thanks. Pity we never found out what results Craig got with the SC trafos. ISTM he was so anal about his interface impedance integrity that he missed the elephant in the room. That being the grounding of the digital in - the SC trafos have the lowest interwinding capacitance I've seen (<1pF) so would have the best chance of mitigating the CM noise.

 

[Gintaras]

+1

 

[FrankCooter]

+1

+2. Runs with my Audio Note 2.1B.

 

[BoxerOrBag]

Hi, I have an Octave 2 on the way, just wondering if the consensus right now is to get an external clock (ie USB to SPDIF converter) for the DAC. If so, what are the recommendations?

 

[Clemmaster]

Hi, I have an Octave 2 on the way, just wondering if the consensus right now is to get an external clock (ie USB to SPDIF converter) for the DAC. If so, what are the recommendations?

The Octave has a really good USB input according to the reviews. Unlike its brother, it DOES make use of the (sometimes) dirty USB power; you might want to add something to clean this. Either a USB cable with separated power and data and a battery to supply power, or, more simple, a iUSB power.

 

[zenpunk]

Be aware that the M2tech Hiface used in the Octave II isn't compatible with Apple's new OS: Maverick.

 

[Clemmaster]

Be aware that the M2tech Hiface used in the Octave II isn't compatible with Apple's new OS: Maverick.

No workaround for that?!

 

[BoxerOrBag]

The Octave has a really good USB input according to the reviews. Unlike its brother, it DOES make use of the (sometimes) dirty USB power; you might want to add something to clean this. Either a USB cable with separated power and data and a battery to supply power, or, more simple, a iUSB power.

 
thanks, I happen to have an iUSB lying around ( it does zilch for my other DACs)
 

  Be aware that the M2tech Hiface used in the Octave II isn't compatible with Apple's new OS: Maverick.

 
Crap! thanks for the warning
 

No workaround for that?!

 
see top of page...((
 
http://www.m2tech.biz/hiface.html

 

[mock-up]

Bump

 

[paradoxper]

M2tech still hasn't released updated drivers. There seems to be messy workarounds however. Metrum specifically seems to have
some 'pay for fix' in the works. I'd be pissed.. that is, they (Metrum) dropped M2tech so wait for their new solution..

 

[Zoo Animal]

It sounds like they are going away from M2tech
http://www.digitalaudioreview.net/2014/04/metrum-acoustics-lose-patience-with-m2tech-over-mavericks/
 
Metrum wasn't the only one to use the M2tech interface, there are likely a few that are looking for solutions elsewhere.