I am a tube person as that is my preference. I have not heard a SS DAC that compares for dimension, air and separation, etc. All of the comments above have some truth in the price range those DACs fall into. R2R is my preference but we have build Sabre 32 BIT Chip DACs that also are fantastic. We also have modified or heard most of them many times. What makes a reference component is the power supply and the parts used. Most DACs use many capacitors in the power supply, nice but nothing special (think the $43,000 DaVinci - Light Harmonic). Excellent sounding DAC but to our ears not reference quality. The design separates them apart and like mentioned above most sound very similar. Once you get into the design of the power supply and how the parts are used in the design then you will understand what makes something sound the way it does. The use of chokes versus resistors and capacitors, V-Capacitors, Audio Note, etc. Even the Audio Note while using really good parts to our ears is not a reference sounding DAC.
Happy Listening.