Wyred4Sound DAC-2 AND STI-500 Integrated Stereo Amplifier


On the Bench

Since the STI-500 is a fully balanced amplifier, I was unable to test it on my equipment, as it does not support measurements on those devices. For the DAC-2, all measurements were done at 16/44.1 resolution as the current measurement software has an issue with Windows 7 at rates higher than that. The output signal was the optical output from my computer.

At 1 kHz, the THD+N numbers for the DAC-2 were very low at 0.00448% with only one noticeable peak at 3 kHz that was over 85dBV below the peak frequency.

Moving on to a 10 kHz signal, the THD+N drops down to 0.0012%, with over 100 dBV between the peak frequency and the closest peak.

On the 19 kHz, 20 kHz IMD test, the IMD number is very low at 0.0025%, and the peaks are again over 85 dBV above the lower peaks.

On 60 Hz, 2 kHz, the IMD number stays very low at 0.0058%, with side peaks at 4 kHz and 6 kHz, each more than 80 dBV below the main peaks.

On 60 Hz, 7 kHz, IMD is almost identical at 0.0059%, with a side peak at 14 kHz that's around 85 dBV below the main peaks.

The frequency response of the DAC-2 is basically flat out to 15 kHz, and then has a very slow and gradual roll-off of around 3db out to 20 kHz.

Overall, the DAC-2 has posted fantastic results on the bench.

Though I was not able to test the STI-500 myself, Wyred4Sound was nice enough to run the unit through their Audio Precision test device using the same specifications that we would use for our own testing, though we were not able to witness the testing ourselves.

With 5V output for a 1 kHz sine wave, the STI-500 measures around 0.01% of THD+N at both 4 and 8 ohms.

Moving up to 20V output, the THD+N doubles on the 8 ohm load and triples on the 4 ohm load, but the secondary peaks are still 70 to 85 dBV below the 1 kHz peak.

The frequency response at 5V has a slight roll off of around 0.3 dBV from 20 Hz to 20 kHz at 4 ohm, and a roll off at 8 ohm that is the same, but flattens out at around 20 kHz.

At 20V of output, the frequency response roll-off looks to be almost identical as at 5V.

Here we see the power output into 4 and 8 ohm loads graphed against THD+N. For most of the output range it stays below 0.01%, with the knee in the graph occurring right around 0.03% for both loads.

In these two graphs (the first is 8 ohm, the second is 4 ohm), we see that at 8 ohm, the THD+N is flat out to 1 kHz, then there is a rise from 1 kHz to 10kHz where the THD+N triples, then goes back down to its original level by 20 kHz. With the 4 ohm load, the THD+N starts to rise by 30 Hz, cresting at 5 kHz, and then falling from 10 kHz down to 20 kHz, with a peak value that is close to 10 times the THD+N numbers at 20 Hz. However, even these peak numbers are still fairly low at under 0.035% THD+N.