In this blog post I test the Schiit REKKR amplifier.
Features:
- Stereo, 8 Ohms: 2W RMS per channel
- Bridged Mono, 8 ohms: 4W RMS
- THD: <0.001%, 20Hz-20KHz, at 1V RMS into 8 ohms
- MD: <0.001%, CCIR, at 1V RMS into 8 ohms
- Size: 5” x 3.5” x 1.25”
- Weight: 1 lbs
- Designed and built in Texas USA
The Schiit REKKR has a cool name...it reminds me of Commander Riker from Star Trek Next Generation. I decided to purchase the REKKR and see how the unit does on the test bench as well as listening.
For listening I hooked the REKKR up to my 2095 speakers rated at 98dB (anechoic) or 105dB (in-room, aka Klipsch rating). I was pleased with what I heard. The highs were smooth and detailed, with no hint of harshness. The treble was a little more pronounced than my KT88 Single Ended amplifier.
I found that the REKKR sounded great until I tried to push the volume past 75dB at which point soundstage depth and clarity suffered. I put a digital voltmeter on the output jacks while the music played and I got around 0.40-0.75V for reference. This will be important later.
I then decided to place the REKKR on the test bench to see how it measures. Starting with harmonic distortion at 0.06V. We can see that we are well in to the noise floor of the amplifier, so let's increase the output.
Testing at 0.25V is shown below. We can see that we've started to pull out of the noise but are not quite there yet.
At 1.00V (shown below) we can see that distortion for the 10kHz region is 0.01% for H2,H3, and H4.
For the 4.00V output (shown below) distortion remains at or below 0.01% for the midrange and treble region. Bass peaks at 1% for the 100Hz region. 
Conclusion on Harmonic
The REKKR has very low harmonic distortion compared to most tube amplifiers I've tested which would have elevated levels of H2 and H3 usually around 0.10% for the 1.00V output, with H4 usually very low similar to the REKKR. The REKKR has similar distortion performance in the bass as most tube amplifiers I've tested are at around 1% for the the 1.00V output.
In terms of comparing other solid state amplifiers, the REKKR does very well. For example, below is the Emotiva UPA-700 at 1.00V. We can see that treble distortion rises with the Emotiva, but excels the REKKR in the bass at only 0.07% compared to 1% with the REKKR.
Intermodulation Distortion
Conclusion on IMD
The REKKR has -85dB noise floor for the 1.00V test signal, but as you can see, the amplifier goes into hard clipping at 2.00V. This is still less than 1w output.
I decided to bridge the amplifier to see if I could get more power. I found that the amplifier would go into protection at anything above 1.30V output when configured in bridged mode. So in terms of music, the bridged configuration offered less power output than in stereo driving a single channel. Go figure.
I then decided to measure the IMD on my KT88 single ended amplifier. The 1.00V test voltage is shown below. As you can see we only have about -60dB of dynamic range.
If we look at the Emotiva UPA-700 at the 1.00V, we have -76dB of dynamic range. So the REKKR beats this by about -10dB. Very Good for a $150 USD amplifier!
Again, for comparison, the Rogers Sound Lab IA255.1 ULTRA-COMPACT INTEGRATED AMPLIFIER at 1.00V is shown below. We have -73dB dynamic range for the 10kHz region on the Rogers compared to -85dB for the Schiit.
Gedlee Metric Distortion
Measuring Gm distortion at the various output voltages is shown below.
Red: 0.06V
Green: 0.25V
Blue: 1.00V
Purple: 4.00V
For the 1.00V output we can see that Gm is very low for the treble region (blue trace). This correlates to what voltage sounded best in my listening test (0.40-0.70V).
Below is a comparison between the REKKR and my KT88 amplifier for the 0.25V output. As you can see, the REKKR does well except for the bump at 180Hz.
Conclusion on Gm Distortion
The REKKR does well at keeping noise and distortion low even at very low output levels. In other words, this is a very quiet amplifier making it suitable for very high sensitivity speakers or for desktop applications. I detected no hiss from the amplifier even when connected directly to a 108dB sensitive compression driver.
Final Conclusion
The REKKR does well especially above 3kHz where Gm distortion drops below 0.001. For example the ACA Mini tested here could not achieve this distortion performance. The harmonic distortion is generally very low through the midrange and treble with none of the prevalent H2 and H3 that we get with tube amplification, so don't expect this amplifier to add any harmonic richness to this part of the frequency spectrum. However H2 and H3 is elevated in the bass, approaching 1% which may add some beefiness (thickness?) to this region. The IMD was extremely low, even at the limit of my test equipment for the 1.00 test voltage indicating that performance should be even better than what I'm measuring.
The REKKR sounded best in the 0.70V output voltage which is around 1/10 of a watt. This is typical for most low to medium listening levels for desktop applications, or in my case extremely high sensitivity speakers in a large room. The REKKR did not achieve the specified power rating of 2w in my test. I was only able to get about 0.27 watts maximum with a music signal (12 tones/octave multitone) before distortion quickly set in (see 2.0V IMD result). Overall I would recommend the Schiit REKKR for it's great subjective sound quality with all of the caveats provided.