I recently spent a few quality days with the Holo Spring Level 3 DAC, courtesy of Sound Affairs, Singapore distributor for Holo. There is plenty of chatter in various audio forums on the Holo Spring DAC, especially on the high level of performance it delivers for it's price.
The Holo Spring is a really nice looking DAC (I adore those copper side panels), and is solidly built. It probably has the largest display I've ever seen, and the dot matrix panel is fully legible even from my listening position.
The Spring DAC is a R2R DAC design. What differentiates the Spring from the rest of it's competition is that fact that DSD is decoded using a R2R circuit too. This is achieved by having two separate R2R circuits - one for PCM and the other for DSD.
The front panel has four buttons. The first button puts the DAC in standby mode, while the rest of the buttons control the display intensity, oversampling mode and source. There are four oversampling modes, NOS (no over-sampling), OS (both PCM and DSD are oversampled in their native format), OS PCM (oversampled PCM - DSD is converted to PCM), and OS DSD (oversampled DSD - PCM is converted to DSD).
The rear panel has both single-ended and balanced analog outputs, while a total of 6 digital inputs are offered - USB (galvanically isolated), coaxial, BNC, AES, Toslink and I2S via HDMI (PS Audio standard).
In use, the Spring DAC runs quite warm. It was left powered on for the few days I had it in my system.
Dimensions wise, the Spring DAC measures 430 mm x 300 mm x 55 mm, and weighs 8.5 kg.
I was not able to do detailed comparisons of the Spring DAC using various digital inputs or its oversampling modes due to the short evaluation period I had. However, I did find that NOS mode sounded the most pleasing to my ears, while the tone of the unit was similar via SPDIF and I2S. I had a slight preference for I2S (fed via a Singxer SU-1 USB / SPDIF bridge) and stuck to that.
To be continued ...