joe_cool
1000+ Head-Fier
Well, it's Saturday night and the heavy rollers are off-line, so I decided to post a mini-review on the DR DAC2 which I recently bought from Korea via eBay. It was delivered via UPS in less than 48 hours.
This is a small unit with a lot of built-in functions. It has 24/96 USB input (no driver required) as well as Toslink SPDIF, coax SPDIF, and analog stereo inputs. There are Toslink SPDIF (AC3 pass-through supported) and line-level stereo analog outputs as well as two headphone outputs with low-gain and high-gain configurations. All analog outputs are controlled by the front-panel Alps potentiometer.
Included is a small 15VDC switching power supply rated at two amps and good for 110 or 220 volts AC input. Also there is a 5-foot USB cable (A-B) with a donut choke on the peripheral end, a multi-language instruction manual and some small adhesive-backed silicone bumper feet.
My first impression was about the small size of the unit relative to the weight of the box. The power supply is very light so most of the weight is in the main unit. Some will wonder if sonic improvements could be gained with a linear DC power supply, but in my mind this is doubtful as the internal power supply is obviously a switcher with multiple output voltages.
My areas of interest in this unit are the USB interface, the headphone amplifier and of course the DAC itself, which is a BB1798 with differential current outputs. The DAC analog section includes 3 dual op-amps so there is an I/V converter for each output and a converter/filter for each channel. After a quick listen I replaced the stock 5532 op-amps with 3 x LM4562NA which improved the resolution considerably.
The line output (after the volume control) uses an OPA2134 and the headphone amp uses an OPA2604 driving a complex discrete-transistor array. I didn't attempt to trace the circuit but there appear to be 32 discrete transistors on both sides of the PCB including the 4 larger output devices.
In general I would rate the USB input as very good. I noticed no obvious jitter when driven by the USB2 ports on my Asus P4P800SE using several high-grade cables.
The DAC section I would rate excellent (at least equal in comparison to my M-Audio SuperDAC with considerable enhancements). There was no problem with 192kHz data but this was tested via coax using my M-Audio Revo5. No testing of the TOSLINK input or output was attempted.
The headphone amp I would also rate very good when driving AKG K701s. The low-gain jack gave the best sound but head-bangers will want to use the high-gain jack for dangerous volumes.
Improvements in the line-out and headphone amps are likely possible with better op-amps. I would consider the BB OPA2107, 2x OPA627, 2x AD825 or AD8620 for the line-out. Higher gain-bandwidth may be required for the headphone amp and I would recommend 2x AD825 or AD8620. The analog PS is +/- 12VDC.
I will try to post pics and further impressions when time permits.
This is a small unit with a lot of built-in functions. It has 24/96 USB input (no driver required) as well as Toslink SPDIF, coax SPDIF, and analog stereo inputs. There are Toslink SPDIF (AC3 pass-through supported) and line-level stereo analog outputs as well as two headphone outputs with low-gain and high-gain configurations. All analog outputs are controlled by the front-panel Alps potentiometer.
Included is a small 15VDC switching power supply rated at two amps and good for 110 or 220 volts AC input. Also there is a 5-foot USB cable (A-B) with a donut choke on the peripheral end, a multi-language instruction manual and some small adhesive-backed silicone bumper feet.
My first impression was about the small size of the unit relative to the weight of the box. The power supply is very light so most of the weight is in the main unit. Some will wonder if sonic improvements could be gained with a linear DC power supply, but in my mind this is doubtful as the internal power supply is obviously a switcher with multiple output voltages.
My areas of interest in this unit are the USB interface, the headphone amplifier and of course the DAC itself, which is a BB1798 with differential current outputs. The DAC analog section includes 3 dual op-amps so there is an I/V converter for each output and a converter/filter for each channel. After a quick listen I replaced the stock 5532 op-amps with 3 x LM4562NA which improved the resolution considerably.
The line output (after the volume control) uses an OPA2134 and the headphone amp uses an OPA2604 driving a complex discrete-transistor array. I didn't attempt to trace the circuit but there appear to be 32 discrete transistors on both sides of the PCB including the 4 larger output devices.
In general I would rate the USB input as very good. I noticed no obvious jitter when driven by the USB2 ports on my Asus P4P800SE using several high-grade cables.
The DAC section I would rate excellent (at least equal in comparison to my M-Audio SuperDAC with considerable enhancements). There was no problem with 192kHz data but this was tested via coax using my M-Audio Revo5. No testing of the TOSLINK input or output was attempted.
The headphone amp I would also rate very good when driving AKG K701s. The low-gain jack gave the best sound but head-bangers will want to use the high-gain jack for dangerous volumes.
Improvements in the line-out and headphone amps are likely possible with better op-amps. I would consider the BB OPA2107, 2x OPA627, 2x AD825 or AD8620 for the line-out. Higher gain-bandwidth may be required for the headphone amp and I would recommend 2x AD825 or AD8620. The analog PS is +/- 12VDC.
I will try to post pics and further impressions when time permits.