Monoprice Cavalli Liquid Spark technical measurements If you are unfamiliar with audio measurements please use a search engine with the query: "audio measurements" or "audio measurement handbook" Look for publications by Richard C. Cabot and also by Bob Metzler, both from Audio Precision. There are other useful publications as well. These will provide basic knowledge. Interpretation of the following measurements is beyond the scope of this post. The data presented were collected as follows: 1. PrismSound dScope III, picoscope 5243B, Keysight 34461A DMM 2. 300 and 30 ohm loads used for measurements 3. Unbalanced cables Worlds Best Cable Gotham GAC-2 RCA 4. Vaunix Lab Brick USB hub for measurement equipment 5. Audioquest Forest and Schiit Pyst USB cables used for measurement equipment 6. Amplifier gain adjusted to 0 dB gain @ 0.775 Vrms 0 dBu 7. Spark gain switch set to high position 8. Spark gain knob at approximately 1:00 to achieve 0 dB gain 9. 36V SMPS for power except where noted 10. 14 and 16 AWG sheilded power cables used Reference levels : +9 dBu 300R 16.00 mW - 110 dBSPL @ 98dB/mW 0 dBu 300R 2.00 mW - 101 dBSPL @ 98dB/mW -10 dBu 300R 0.20 mW - 91 dBSPL @ 98dB/mW -20 dBu 300R 0.02 mW - 81 dBSPL @ 98dB/mW +9 dBu 30R 160.00 mW - 110 dBSPL @ 89dB/mW 0 dBu 30R 20.00 mW - 102 dBSPL @ 89dB/mW -10 dBu 30R 2.00 mW - 92 dBSPL @ 89dB/mW -20 dBu 30R 0.20 mW - 82 dBSPL @ 89dB/mW Reference data on two headphones: HD 650 impedance 300R, sensitivity 98 dB/mW HE-500 impedance 38R, sensitivity 89 dB/mW Highlights Square wave response is very near that of the Liquid Crimson. Bandwidth is extraordinary for an amp at this price: DC to > 1.5 MHz Well done Dr. Cavalli! @Hands has posted a review here Schiit Magni 3 measurements, for comparison, found here My personal preferences include listening typically at an average of 75 dB SPL. Assuming a typical Peak to Average ratio of 10 dB puts peaks at 85 dB SPL. This suggests the measurements at -20 dBu represent my experience with HD6x0 and HD800 headphones. Auditory experiences for someone listening 10 dB SPL average higher may diverge from my own experiences. editorial - I believe there is a tendency to focus excessively on numbers such as THD attempting to reduce a complex topic to a single number representing a sort of goodness rating. Graphs can present far more data conveying a better understanding of the measurement over a range of frequency, levels, etc. Please don't read too much into the numbers presented. Read the tutorial presented here for a good example of why. Picture of the Audio Lab setup for Liquid Spark measurements 300 ohm load part 1 of 3 Liquid Spark THD+N THD nth harmonic distortion (A04) FFT 0dBu 300R load Liquid Spark THD THD+N vs Freq 0dBu 300R Liquid Spark 1 KHz spectrum Left and Right 0dBu 300R load Liquid Spark 50 Hz + 7000 Hz spectrum Left and Right 0dBu 300R load Liquid Spark 600 Hz + 1700 Hz spectrum Left and Right 0dBu 300R load Liquid Spark IMD spectrum Left and Right -16dBu 300R load Liquid Spark residual noise spectrum Left and Right A=0dB 300R load Residual noise is very low for an SMPS powered headphone amp.