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A friend asked me to check out the VRS hard drive digital playback system.  I had not previously heard of hard drive digital playback, and frankly I was not a diehard analog fanatic. To me, hard drive music just meant computer playback through a cheap soundcard; something that might work in a study or at the office, but hardly worthy of the high-end system I was in the midst of putting together.  I was wrong - seriously wrong. 

You’ll need to find an external DAC to set up a hard drive digital playback system.  In case you haven’t noticed, your computer does not come with balanced and unbalanced outputs, so you can’t connect it directly to the DAC you may already have; and if you can’t do that, the computer system can’t serve as a digital front end for your rig.

There are basically two approaches one can take at this point.  You can hook your computer up to an external USB DAC, or you can find a converter that will allow you to take the USB signal from your computer and convert it to a signal that a standard/non USB DAC is willing to accept – typically, a SPDIF or AES signal, or, less frequently, an I2S signal.  One company offering these converters is Empirical Audio.  Their converters are called ‘Off-Ramps” or “Freeways.”  The obvious advantage of these converters is that they provide access to the wide range of external DACs that are already available in the marketplace.

I contacted Steve Nugent of Empirical Audio. I first learned of Empirical Audio because of Steve’s well regarded modifications of DACs and standalone CD players of all varieties and at all price points.  He designs his own interconnects which, too, have secured something of a reputation for high performance and good value.

Steve had been designing his ‘Off-Ramp’ converters for some time: a USB to SPDIF or AES converter and a USB to I2S converter. Over time Steve performed mods on his own designs upgrading their performance.  He refers to his best modifications as ‘turbomods’ and in time he discontinued the basic Off-Ramp in favor of the turbo version, which was considerably more popular among his customers anyway.

Steve sent me two Off-Ramp converters – one SPDIF, one I2S; one turbomodded Perpetual Technology DAC, one Battery Power Source for the converters, one pair of Empirical Audio Holophonic-PC interconnects and one CD with some of Steve’s favorite tunes for downloading.

So What’s an Off-Ramp anyway?

Don’t feel bad, three months ago I probably couldn’t have answered that question very well either.  In the case of the USB to S/PDIF or AES converter, Steve begins with the inexpensive M-Audio Transit which he then modifies.  His modifications are designed to reduce jitter, improve the power supply, and improve the integrity of the signal path (check his website for more details).  The Off-Ramp Turbo supports most digital formats including 16/44.1, 24/48, 24/96 (not 24/192), PCM, AC3, MP3, AAC, Apple lossless, FLAC, WMA, and is compatible with all DAC's. In contrast, the IS2 converter is not a mod, but built from scratch.  The I2S interface bypasses the S/PDIF interface further reducing jitter over the Off-Ramp Turbo.  The I2S interface is a 4-wire interface.  I2S is a native interface compatible with most DAC chips, but is currently compatible with 3 DAC's, Perpetual Technologies P-3A, Northstar 192 and Benchmark DAC-1 with I2S mods.  Both the S/PDIF and I2S turbos are sold factory direct for $950.00 and the BPS for $450.00.  The AES version goes for $1050.00.

I hooked up the PT DAC to the computer using the USB/SPDIF converter and the standard wall-wart power supply.  I would then try the same setup but substitute the BPS for the wall wart.  Then I would go back to the wall wart and remove the Off-Ramp Turbo in favor of the I2S converter.  I would then reintroduce the BPS.  During this initial process I would keep everything else in my system constant (as best I could).  Once I had figured out what I liked best and had a sense of the relevant differences, I would consider making changes in speakers and associated amplifiers to test performance in different contexts.

This was probably the most complex experiment I had designed since Freshman Chemistry.

I used the USB cable included with the Brick which connected the computer to the Off-Ramp Turbo, which was connected both to the wall-wart power supply and the PT DAC.  I connected the DAC to my preamp by the same Stealth Indra interconnects that were in use with the Brick and which I have used for over a year to connect from my digital sources to my Shindo Catherine preamp.  Along the way, I tried the Empirical Audio interconnects that Steve had provided me.

Off we go

I played dozens of CDs from the computer and a few tunes streamed from the internet with the system configured in this way.  The Off-Ramp Turbo/PT configuration was terrific in almost all respects. The sound was balanced, tonally neutral, dynamic and very detailed and focused.

I was struck most by the similarity of sound between the transport/DAC and computer/DAC setups.  This was very comforting because it meant that going from a high-end transport to a computer would not mean giving up much, if anything, by way of sound in order to achieve greater flexibility and convenience.

So far so good

I then introduced the battery power supply which proved to be something of a minor revelation.  The presentation relaxed considerably. Music seemed less rushed and anxious.  I much preferred this combination to the one with which I had begun and thus I recommend the BPS accessory without qualification.  There was a slight loss in macro dynamics which was more than offset by an increase in micro dynamics, as background became darker still. The trace of hardness in the presence region was minimized and while I was not enamored of this feature of the DAC, there was no question but that the Off-Ramp Turbo was performing as advertised.

And now for something much better.

After listening to the system configured in this way for a couple of weeks and really enjoying it – so much so that the only time I realized that I was using a computer/hard drive system was when I was aware of how much more convenient playing music had become. 

During this time the I2S converter arrived and it was time to see what difference it might make to digital playback.  Frankly, had the I2S converter never arrived, I would have been very happy with the setup as is.  In fact, I would have been happy to have the Off-Ramp Turbo/PT DAC serve as a digital reference. That’s how good it was.

But the I2S did arrive.  So I removed the BPS and replaced it with the wall wart again and removed the SPDIF converter in favor of the I2S converter.  Be warned, the pins on the I2S cable that connects the Off-Ramp I2S to the PT are delicate and bend easily.  If they do, the cable won’t work. 

Be warned.  Once you succeed at hooking up the I2S converter to the DAC, you may not be able to return to any other sort of interface.  That’s how wonderful the combo sounded and right from the get-go.  If anything, the resolution and focus improved – which would have been hard to imagine had I not heard it myself.  Resolution improved in the only way that makes sense to me; that is, notes arrived, unraveled and decayed naturally and in the right relationship to one another.  Focus too improved in terms of transparency to the back of the soundstage.  In conjunction with the Peak Consult Zoltans which are themselves masters of soundstaging and focus, the combination was lethal; that is, killer.

More than that, there was an unmistakable naturalness to the presentation that was more reminiscent of the Reimyo’s presentation than that of which the previous combination was even capable. I couldn’t tell whether it was the Off-Ramp I2S or the use of the I2S input that made the difference, but I didn’t care. The Off-Ramp I2S was the only way to get to the I2S input on the DAC and it provided a very smooth way to get there.  And I was happy to be there.  The sound was now approaching a truly exceptional digital set up, and I much preferred this combination to the Revox/PT DAC.  I had to remind myself that my transport was no more than an Apple Powerbook.

Batter-y up

All that remained was to reintroduce the BPS, which I did a couple of days later.  The BPS had the expected result, but the impact was less dramatic. Background noise was reduced a bit further; everything became just a tad more transparent and relaxed but at a minor cost to macro dynamics.  The loss in macro dynamics is more than offset by an increase in micro dynamics discernable in virtue of the improvement in transparency and reduction in background noise.

Summing up

When I took the plunge into computer and hard drive digital playback, I did not do so reluctantly, but with some hesitation. In the first place, no one really thinks that the internal environment of a computer is the best neighborhood for an audio signal.  A good transport will always sound better than a computer will. Let’s not forget that computer playback has the advantage of bit-by-bit playback.  There are no misreading errors.  A bit more noise: yes; but a lot more precise reading of the information. 

My more pressing concerns had to do with external DACs.  How many would work with a computer, and how well would they work?  If the Brick is any indication, the new generation of USB based DACs are going to be just fine; in fact, much better than that.  I’m confident that there are probably excellent USB DACs available right now and the promise of more to come. But USB DACs aren’t in plentiful supply just yet and designing a successful USB DAC is not child’s play.  There are serious problems that need to be addressed in any USB DAC.

On the other hand, there are a large number of quiet, outstanding traditional external DACs already available on the market and others on the way.  Many music lovers already own such DACs and their reluctance to switch over to a significantly more convenient and flexible computer system is grounded in a fear that the sonics will be significantly compromised. 

I’m here to tell you that it isn’t so. If you like the sound of your DAC, the various Off-Ramps available from Empirical Audio mean that you will not have to shop for a different DAC; more importantly, the Off-Ramp will enable you to extract the entire sonic splendor that your DAC has to offer.   In particular, the I2S converter is a revelation and it left me wishing that more DACs were fitted with I2S inputs.  The battery power supply is another must have.

Another reason for fearing the future has disappeared and we have Steve Nugent to thank for that.  With so many USB DACs on the horizon and with Empirical Audio’s incredible Off-Ramps already available, it is a very bright future indeed.