About 3 weeks ago I began breaking in an Off-Ramp Turbo, and have over 500 hours on it. I have just finished comparing this USB input to SPDIF input on my system. Overall, I wouldn't call it a contest. But here are some thoughts.
Cyrus Chestnut - Revelation - Lord, Lord, Lord
The USB passes more low level information, with background sounds easier to identify; there is some humming in this track. The piano note attack is cleaner and there is more resonance to the note, a better sense of the sound as it progresses through the note - beginning, middle, and end. Instruments are more clearly defined and separate. There is more texture to the bass strings.
Bill Frisell with Dave Holland and Elvin Jones - Outlaws
The soundstage w/USB is much deeper and wider, with much more instrument resonance. The bass lines are cleaner and the cymbal sounds hang in the air.
Roy Hargrove - Public Enemy - End Of a Love Affair
Off-Ramp provides a rounder trumpet sound, and more texture is evident in the fine brush work.
Eagles - Hell Freezes Over - Get Over It
Noticeably more impact to notes and a more authoratative floor to the music. The tom-toms in the middle of this track have more air around them and more reverberation. USB provides a more enveloping sound.
Dallas Wind Symphony - Pomp and Pipes - Vikings From Finland Suite
Much more hall realism, soundstage width/depth, reverberation, more immediacy. There is greater bass impact and it is easier to discern the note attack on brass instruments.
Ray Charles - Genius Loves Company - Fever
The Off-Ramp version is more involving with more drive from the rhythm section. Voice inflection is more apparent for both Natalie Cole and Ray Charles. A more tangible presentation.
Gene Harris - Best of the Concord Years - Captain Bill
Cymbals come in early in this track in the background, and are less fuzzy w/USB and more clearly cymbals rather than just a high frequency sound. The intonation of notes for the sax is clearer.
There really isn't a quality that wasn't improved going from SPDIF to Off-Ramp. It's easier and more enjoyable to listen at low levels because the sound remains clear, and easy to listen at high levels because the sound isn't irritating or grating. The SPDIF is not harsh either and sounds fine until you make a comparison, then it seems you sucked out much of the life of the music.
I was worried when I first hooked up the USB. The sound was harsh, edgy, and all over you. It was better at 200 hours and better at 300 hours. The V-Caps must want a lot of time to settle in. So far, I prefer to have Foobar set to 16bit with no resampling, and the Transit then set to 16bit. SPDIF out was clearly better than the Meitner CDD transport that I was using before, but the USB is a hands down winner to digital cable.
The only uncertainty with this comparison, is that I don't know how well the Luminous Audio Allegro cable stacks up. I was using a Green Hornet digital before, but sold it when I ordered the Off-Ramp.
I don't think you would be disappointed in the performance of the Off-Ramp. It provides an involving, clear window across different types of music.
