Update I: my review of the HILO has been published at Headfonia.
Update II: I have updated this section with both 16 and 24 bit line output RMAA scores as well as 16 and 24 bit headphone output RMAA scores.

Disclaimer: HILO was tested via its own inputs and outputs, not via external, professional analysing equipment.

I have the LT-TB version of the Lynx Studio HILO ADC/DAC (~3000$) in office for another week, in which time I will continue to evaluate it as a pre-amp, a DAC, a headphone amp, as well as an ADC. My full review of it will be published at Headfonia. While I've not had time to formulate hard opinions on its DAC sound quality, I can say this: its ADC is as good as it gets this side of an audio analyser. Below are 16 and 24 bit / 44kHz RMAA test results for both its line and headphone outputs.

The following are the results of Rightmark Audio Analyzer tests.
Source: Lynx Studio Technology HILO
ADC: Lynx Studio HILO LT-TB
Computer: 2012 27" iMac
Cables: 1,5m Hosa Pro 3,5mm stereo to dual 3-pin XLR (around 8$); typical XLR microphone cables

Loads:
NL - no load
SM2 - Earsonics SM2
ES7 - Audio Technica ES7
DT880 - Beyerdynamic DT880/600

As you can see, both its main ADC and DAC exceed the limits of 16-bit audio, and scores very respectably in 24-bit tests.

Line output RMAA results (16 and 24 bit):