After spending two weeks with this low priced headphone amp, I have to say I am
really enjoying it. Warm sounding, strong bass, exceptional mid-range and easy-on-the-ears highs.
Listening to music with the HD-650 headphones, I had been using the popular upgraded Crack amp with tube upgrades.
I hate to say it, but I haven't turned that amp on since I started using the Spark.
There are problems with the Spark, as you would expect with a $100 amp.
I'm glad that fatigue is not one of them, something that does hinder low cost amps.
There are many reviews out there so I won't try to top them
http://www.enjoythemusic.com/magazine/equipment/1018/Monoprice_Monolith_Liquid_Spark_Headphone_Amplifier_Review.htmMost music is played from Tidal through Audirvana 3 and a Holo Spring Level 3 dac.
Jeff