Monoprice Cavalli Liquid Platinum 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, Micsig DP10013 balanced probe, Keysight 34465A DMM 2. 300 and 30 ohm loads used for measurements 3. Balanced cables Canare L-4E6S starquad with Neutrik XLR connectors 4. Unbalanced cables Worlds Best Cable Gotham GAC-2 RCA 5. Vaunix Lab Brick USB hub for measurement equipment 6. Audioquest Forest and Schiit Pyst USB cables used for measurement equipment 7. Amplifier gain adjusted to 0 dB gain @ 0.775 Vrms 0 dBu 8. Platinum gain knob at approximately 11:00 to achieve 0 dB gain Bal, 1:00 for 0 dB gain SE 9. Stock EH6922 tubes used 10. 36V SMPS for power except where noted 11. 14 and 16 AWG sheilded power cables used Reference data on two headphones: HD 650 impedance 300R, sensitivity 98 dB/mW HE-500 impedance 38R, sensitivity 89 dB/mW SPL levels for above headphones for reference: +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 All testing performed at 0 dBu unless otherwise noted. This level is consistent with listening to headphones referenced above at 90 dBSPL average with peaks to 100 dBSPL, if the music has 10 dB Peak to Avg ratio. Highlights First, well done Dr. Cavalli! This is an excellent addition to the family. Square wave response is very near that of the Liquid Crimson, with only a very slight ring on rising and falling edges. Bandwidth is quite wide: DC to > 670 KHz The Liquid Platinum provides excellent performance Single Ended in and TRS out, but is much improved SE in and 4-pin 4XF out. If contemplating this amplifier, balanced headphone cables will prove a wise choice. However, this amp is optimized for balanced use. Bal in and 4XF out yields the highest performence LP has to offer. Liquid Crimson still has the edge in a few areas such as transient response, but is rare, pretty much unobtainium and Single Ended operation only. Liquid Platinum is mostly at parity with Liquid Crimson running SE, and has the advantage of availablity. Running balanced input and output is measures nearly a dual mono system. Crosstalk is exceptionally low. Residual noise is lowest with fully balanced operation. The supplied SMPS works well having low noise in the audio band. Liquid Platinum audio measurements did not demonstrate significant difference between SMPS, SMPS+NoiseNuke and BK1623A LPS. Power supply spectrum measurements did show lower noise for SMPS+NoiseNuke and LPS over the SMPS provided. The following LPS is arriving sometime in the next 30 days and will be tested as time permits: Zero Zone 36V 1.2A LPS https://www.ebay.co.uk/itm/223064418072 Bottom line As with the Liquid Crimson, Liquid Platinum is another amp that won't be departing my acoustic lab inventory. Test Data Measurements posted are representative of Liquid Platinum's performance but are only a subset of the possible combinations. Consider the following: 30 measurements per combination 2 impedances 30R and 300R per combination 2 input combinations, Bal and SE 2 output combinations, 4XF and TRS 3 power supply combinations That would be at least 720 measurements total!! Some repeats are often necessary for measurement quality verification. Easily 1200 measurements possible. As it was, 450 were performed and 275 documented over a period of 3 days of intense effort even when aided by scripts and automation. These are the most representative of the combinations possible. Test Data Organization Post / Topic 1 introduction 1 - Bal input to 4XF output 300R load part 1 of 3 2 - Bal input to 4XF output 300R load part 2 of 3 3 - Bal input to 4XF output 300R load part 3 of 3 4 - Bal input to 4XF output 30R load part 1 of 3 5 - Bal input to 4XF output 30R load part 2 of 3 6 - Bal input to 4XF output 30R load part 3 of 3 7 - SE input to TRS output 300R load part 1 of 3 8 - SE input to TRS output 300R load part 2 of 3 9 - SE input to TRS output 300R load part 3 of 3 10 - SE input to TRS output 30R load part 1 of 3 11 - SE input to TRS output 30R load part 2 of 3 12 - SE input to TRS output 30R load part 3 of 3 13 - SE input to 4XF output 300R load part 1 of 3 14 - SE input to 4XF output 300R load part 2 of 3 15 - SE input to 4XF output 300R load part 3 of 3 16 - SE input to 4XF output 30R load part 1 of 3 17 - SE input to 4XF output 30R load part 2 of 3 18 - SE input to 4XF output 30R load part 3 of 3 19 - Power supply comparisons SMPS, SMPS+NoiseNuke, LPS part 1 of 3 20 - Power supply comparisons SMPS, SMPS+NoiseNuke, LPS part 2 of 3 21 - Power supply comparisons SMPS, SMPS+NoiseNuke, LPS part 3 of 3 22 - reserved for possible additional measurements 23 - reserved for corrections FLIR temperature measurements 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 Platinum measurements Bal input 4XF output 300 ohm load part 1 of 3 Liquid Platinum THD+N THD nth harmonic distortion (A04) FFT 0dBu 300R load Liquid Platinum THD THD+N vs Freq 0dBu 300R Very even, low distortion across frequencies!! Liquid Platinum 1 KHz spectrum Left and Right 0dBu 300R load Liquid Platinum 50 Hz + 7000 Hz spectrum Left and Right 0dBu 300R load Liquid Platinum 600 Hz + 1700 Hz spectrum Left and Right 0dBu 300R load Liquid Platinum IMD spectrum Left and Right -16dBu 300R load Liquid Platinum residual noise spectrum Left and Right A=0dB 300R load Look carefully at that last graph. Residual noise is non-existent, with provided SMPS. All of the above measurements (and those following) represent engineering excellence. Well done Dr. Cavalli!