This is a review and detailed measurement of the Minidsp Flex audio signal processor. It was sent to me by the company and costs US $475 for unbalanced and $550 for balanced that I tested.
Flex borrows the interface from SHD and puts it in a compact package. Seeing how I really liked that interface with nice volume control, this is a very good move.
Back panel shows why this product is so useful:
Not only do you have a suite of digital input but also analog. More importantly, you can rote any input to any output and apply crossover, parametric EQ filters and compression. The software interface is mostly intuitive except for channel routing which required a bit of looking around.
The supplied remote control allows you to eliminate any need for a preamplifier and drive a power amp directly.
Minidsp Flex DAC Measurements
I alternated between Coax S/PDIF input and USB although performance is the same in both. Here is our dashboard:
OK, I was not ready for this. A multifunction device with DSP that has a SINAD (relative sum of distortion and noise) to rival and outperform many dedicated DACs?
Among its own category which is a mix of DSP and AV receivers and processors it sets a new high bar:
First of its kind to land in the blue "excellent" category!
Above was with the volume at -0.5 dB. There is a bit more performance if you set it to 0:
Dynamic range is very respectable for this class:
There is something holding IMD distortion back though:
This causes the same limiting in multitone:
JItter test shows some interference but they are at such ridiculously low level that bother the eye far more than any ear could ever detect them:
DAC filter is the typical default "lazy" ones in DAC chips:
This hurts THD+N versus frequency a bit but the outcome is still good:
Linearity is excellent:
Minidsp Flex Analog Input Measurements
Some people have an analog only path (e.g. for turntables) and would still want to implement active speakers and/or equalization for room modes. Let's see how we do here:
I am amazed once again! End to end performance this good? Remember this is the performance of ADC and DAC combined. And we still manage to have distortion at < -110 dB (18+ bits).
Dynamic range suffers a bit naturally but still, quite good:
I was relieved to see wide and flat response:
So unlike many AV products that resample everything to 48 kHz, here we have end to end sample rate of 96 kHz (my guess). Bandwidth is in excess of 35 kHz.
Crosstalk was superb:
This is better than countless stand-alone preamps!
THD+N vs frequency again shows no frequency dependence:
IMD performance is again limited by DAC performance:
EDIT: Post review question was raised about performance of channels 3 and 4. Here is that dashboard:
As you see, performance is just as excellent as channels 1 and 2.
Another question was performance drop when using RCA input to TRS balanced adapter:
This is definitely the case. That said, highest distortion component is at -96 dB which is the same as 16 bit audio dynamic range. This is well above what analog sources such as LP can achieve. So I would not worry about it if this is the configuration.
Conclusions
What a nice combination of functionality, usability and performance! As with many DAC companies, it is clearly Minidsp has put strong focus on chasing away sources of noise and distortion. Yes, there is some work left to do with intermodulation distortion but other than that, measurement after measurement put a smile on my face. All AV processor and receiver companies lose any excuses they have for not providing this level of performance seeing how the Flex also implements various signal processing modules.
It is my pleasure to highly recommend Minidsp Flex audio signal processor, DAC and ADC. You made my day!
Flex borrows the interface from SHD and puts it in a compact package. Seeing how I really liked that interface with nice volume control, this is a very good move.
Back panel shows why this product is so useful:
Not only do you have a suite of digital input but also analog. More importantly, you can rote any input to any output and apply crossover, parametric EQ filters and compression. The software interface is mostly intuitive except for channel routing which required a bit of looking around.
The supplied remote control allows you to eliminate any need for a preamplifier and drive a power amp directly.
Minidsp Flex DAC Measurements
I alternated between Coax S/PDIF input and USB although performance is the same in both. Here is our dashboard:
OK, I was not ready for this. A multifunction device with DSP that has a SINAD (relative sum of distortion and noise) to rival and outperform many dedicated DACs?
Among its own category which is a mix of DSP and AV receivers and processors it sets a new high bar:
First of its kind to land in the blue "excellent" category!
Above was with the volume at -0.5 dB. There is a bit more performance if you set it to 0:
Dynamic range is very respectable for this class:
There is something holding IMD distortion back though:
This causes the same limiting in multitone:
JItter test shows some interference but they are at such ridiculously low level that bother the eye far more than any ear could ever detect them:
DAC filter is the typical default "lazy" ones in DAC chips:
This hurts THD+N versus frequency a bit but the outcome is still good:
Linearity is excellent:
Minidsp Flex Analog Input Measurements
Some people have an analog only path (e.g. for turntables) and would still want to implement active speakers and/or equalization for room modes. Let's see how we do here:
I am amazed once again! End to end performance this good? Remember this is the performance of ADC and DAC combined. And we still manage to have distortion at < -110 dB (18+ bits).
Dynamic range suffers a bit naturally but still, quite good:
I was relieved to see wide and flat response:
So unlike many AV products that resample everything to 48 kHz, here we have end to end sample rate of 96 kHz (my guess). Bandwidth is in excess of 35 kHz.
Crosstalk was superb:
This is better than countless stand-alone preamps!
THD+N vs frequency again shows no frequency dependence:
IMD performance is again limited by DAC performance:
EDIT: Post review question was raised about performance of channels 3 and 4. Here is that dashboard:
As you see, performance is just as excellent as channels 1 and 2.
Another question was performance drop when using RCA input to TRS balanced adapter:
This is definitely the case. That said, highest distortion component is at -96 dB which is the same as 16 bit audio dynamic range. This is well above what analog sources such as LP can achieve. So I would not worry about it if this is the configuration.
Conclusions
What a nice combination of functionality, usability and performance! As with many DAC companies, it is clearly Minidsp has put strong focus on chasing away sources of noise and distortion. Yes, there is some work left to do with intermodulation distortion but other than that, measurement after measurement put a smile on my face. All AV processor and receiver companies lose any excuses they have for not providing this level of performance seeing how the Flex also implements various signal processing modules.
It is my pleasure to highly recommend Minidsp Flex audio signal processor, DAC and ADC. You made my day!
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