Introduction to the Parasound Halo CD 1 Player

The Halo CD 1 is a flagship CD Player from the well regarded, San Francisco based, Parasound. CD Player? Surely I mean ‘DAC with Transport’. Nope. CD player, put your CD in, music comes out. No, you mean it’s part of a server system, the data is stored for later retrieval by a computer system. Well, only if you count the internal buffering and Intel ITX computer running Linux inside the CD 1. In implementation then the CD 1 is quite modern, it’s a computer, dedicated to CD playback only. In practice, it’s an old fashioned (and in this case, that’s good) CD player.

For CD playback I would contend that the act of retrieving a disc off the shelf and inserting it into a player is easier than looking up the same on a computer, especially if you count the time you might have spent ripping and cataloging said CD in the first place. This does of course, require some shelf space and probably alphabetizing your CD’s if not organizing them by genre etc.

With this ‘shelving system’ I have devised you will forgo some whiz-bang computer music catalogue features like shuffle and gosh-dang features such as a hard drive failure.

Ok, computer audio also holds the promise of high res files (finally!). But Parasound is thinking there is more to be wrung from the Red Book format and they are on to something.


  • Design: Redbook CD Player
  • DAC: Analog Devices AD1853
  • Analog Outputs: 1 Pair RCA Unbalanced, One Pair XLR Balanced
  • MFR: 20 Hz – 20 kHz, +0/-0.05 dB
  • THD+N: < 0.06% at 1 kHz
  • S/N Ratio: > 108 dB, IHF A-weighted
  • Crosstalk: < 77 dB at 20 kHz
  • Dimensions: 4.1″ H x 17.25″ W x 13.75″ D
  • Weight: 18 Pounds
  • MSRP: $4,500 USD
  • Parasound
  • SECRETS Tags: Parasound, CD Players, Audio


The Design of the Parasound Halo CD 1 Player

The Parasound website has an extensive white paper on the design of the CD 1:

The CD 1 is a slot loader, the loading mechanism feeds a CD ROM drive instead of a conventional CD drive. The CD ROM drive is connected to a passively cooled Intel ITX computer running the Linux operating system and proprietary software from Holm Acoustics meant to improve the reading of CD disc data. The CD ROM drive runs at 4x the CD Data rate to get a head start on the data, allowing the computer re-read if errors are encountered. Re-reading can occur multiple times, with repositioning of the laser if needed, until there are two reads that match. The data re-reads are limited only by the size of the data storage buffer in the CD 1. If that buffer is about to run out the CD 1 will switch to interpolation mode. Even this process is optimized in that the CD 1 takes care to perform this operation on an isolated section of bad data and then switches back to its normal re-read methods as quickly as possible. According to the white paper the process ‘almost always results in error free data’. I have long wondered just how many errors we might be getting off of discs. After all, a sophisticated Reed-Solomon Error Correcting Code is part of the Red Book standard. Furthermore it would be interesting to know what sort of error rate (not jitter, errors) is typical an S/PDif interface. I am still wondering. I had some email exchanges with Richard Schram and Thomas Holm about the CD 1 and how it works but they couldn’t supply this data. To be sure it would take an exhaustive study of new and old discs to say anything definitive but it would be good to know what kind of numbers we’re talking about and compare players in this regard.

The paper goes on to list an Important take on the benefit of upsampling: “The upsampling process minimizes the staircase step size of the output current from the audio DAC to achieve the smoothest possible DAC raw output without any related aliasing. This is particularly important because large current source changes that exceed the slew rate of the analog op amps.” In the case of the CD 1 data is upsampled by 8x.

It has become almost customary to use multiple DAC chips in high end DACs these days but again the CD one has an interesting angle on the topic and does it differently. If you have dual DAC chips, how well are they matched? I would guess that if the chips came from the same production run then the differences – in both delay from input to output and in the analog sections – would be small. But how small is small? Parasound’s discussion on the subject mentions a figure of a 10 nanosecond difference input to output for a given pair of DAC chips. A small number to be sure but if your clock to those two chips is more precise than that, and in the case of the CD 1 it is (10 picoseconds, or one thousand times more precise), then there is a clear cost to go along with any gain you might get from the dual DAC chips. Some of this cost can be measured in the production as some amount of hand tuning is possible to accommodate the DAC chip differences but of course such tuning is an imperfect process so there is a cost to the sound as well. To avoid all this the CD 1 uses a single AD1853 DAC in stereo mode. The balanced output signal is then generated from the op amps (National LME49990’s) in a differential output mode.

A button on the CD 1’s front panel gives you the option of listening to the analog outputs as driven by LME49990 opamps or via discrete transistor output stages. The discrete output stage is a modernized version of the discrete output stage used in the vintage Parasound D/AC – 2000. The transistors are in a Darlington configuration that operates in the feedback loops of the LME49990s so that the specs for THD and noise are as low as the opamps alone. This seemed to be borne out by Chris Heinonen’s measurements which could detect little or no difference between the two modes.

Of course power supplies are of upmost importance in any hifi. Besides the expected separate supplies for digital and analog, the CD 1 has 12 separate point-of-load power supply voltage regulators spread across the digital and analog realms. This use of multiple regulators is something that, to my knowledge, only Naim used to do but is now being adopted by many of high end manufactures. We are all benefiting.

There’s much more in the whitepaper so I’ll just sum up and say that Parasound and Holm Acoustics have put a lot of engineering into this player. You can see from my photo here that there is heavy isolation between the various circuit functions, a detail which is also covered in the paper.

The output connectors are Neutrik XLR connectors for the balanced outputs and gold-plated Vampire RCA jacks for the unbalanced outputs.

The included remote is a small, mid-weight plastic affair. Not quite what we’re used to for some similarly priced equipment but certainly adequate and not unpleasant to use. The textured bottom is rounded with a protrusion to fit the hand. The top portion of the remote is dedicated to the CD 1 while the bottom is for the JC 2 preamp. There is no facility for repeating a track or entire CD. Probably only an issue when you are breaking in the player or perhaps attached cables.


The Parasound Halo CD 1 Player In Use

One thing you might worry about with a CD ROM drive is noise from the drive itself. The CD 1 uses proprietary software to keep the drive silent while playing a CD. If you press the pause button the drive will start to make quiet whirring sound. If you eject the CD the drive spins down and that’s really the only time I noticed it.

This is a slot loader by the way. The mechanism is quiet and seems to be gentle. When the disc is inserted about 7/8 of the way some tiny elves come to life inside and quickly pull it the rest of the way in. Press the stop/eject button once to stop the disc and a second time to eject. The unit also ejects when it is powered off. You can change this behavior during setup (I never tried this) but I think the default behavior is a good way to go. It prevents mishaps when powering up if a disc were to be left in the unit. When you do power up there is a brief wait, about 10 seconds, while the CD 1 remembers who it is and its singular mission in life.

Upon first plugging in the CD 1 and switching between the analog and op amp output stages I thought I heard a clear advantage with the discrete outputs. The op amp stage had a slight constricted quality that I didn’t detect on the discrete circuit. After break in however, I was hard pressed to tell the difference.

The CD 1 powers both its balanced and unbalanced outputs simultaneously but it does so using the same circuitry so only a fool (i.e., me) would hook them both up at the same time. Choose your interconnect method and stick with it friends. Of course the chosen interconnects will make a difference but what I heard was a slight but clear improvement in most everything using the balanced outs.

Sound from the unbalanced is already stellar to begin with however, in fact this may be the finest player I have ever heard. Using a pair of vintage 0.5m Tara Labs Prism 2200 unbalanced interconnects to my Sim Audio P5.3 preamp the sound was sweet with clear separation of instruments, detailed textures (timbre), highs and lows both extended nicely and no discernible fatigue. In all areas except perhaps vocals the CD 1 bested my long time reference Naim DAC with XPS, sourced from an Emotiva ERC-2. By comparison the Naim had a warmer sound (which seemed to emphasize vocals) but with a cost of some blurring of the midrange and bass. Not as much bass either. The CD 1 excels at rocking out, that is, timing, rhythm and rhythm sections are given their due. Switching to the balanced outputs just brought more of everything. The noise floor lowers a bit as expected and more details are heard throughout, especially in voices. I used Analysis Plus Copper Ovals for this connection. I did most of my listening with the balanced outputs and the CD 1 in Discrete Output mode.

I have found that the details of drum sounds, such as the initial thwack (on a snare or tom) are a good way to demonstrate to non-audiophiles the differences in components. Drum thwacks sound especially natural through the CD 1.

The CD 1 comes with rather plain looking beige power cord. Parasound calls the color ‘Putty’, yes that’s it. The cord seems hefty enough but switching to Shunyata’s affordable Venom 3 brought more delineation in the highs. It did not however bring the expected blacker backgrounds, which is a testament to the design or perhaps to the stock power cord itself. Upgrading to Shunyata’s not-as-affordable Venom HC did blacken the background a bit, allowing some incredible vocal details to come through but perhaps an over emphasis on bass. On Lucinda Williams Essence I heard extra breathiness and warble, making an already moving experience all the more so. But on Portishead’s Roseland NYC Live and other discs the black background with this power cord on the CD 1 seemed to rise up and swallow some of the music.

I have the Benchmark DAC2 HGC on hand for review as well. Connected to the CD 1’s BNC digital out with a Nordost Norse 2 and then using the balanced out from the Benchmark. The Benchmark DAC put a very slight veil on the music, but added more interesting texture to vocals and midrange instruments. Only the use of the expensive Shunyata Venom HC brought the DAC2’s noise floor down to the range of the ultra quiet CD 1 however.

The standalone DAC certainly benefited from the CD 1’s error free digital stream by the way. I tried using the Emotiva to drive the DAC and it was nowhere close. It’s the kind of thing that seems un-listenable by comparison. I’ll investigate this further in the DAC 2 review.


The Parasound Halo CD 1 Player On the Bench

As the Halo CD1 is a redbook CD player, the only tests performed were with 16/44.1 content. The Halo CD1 can run in Discrete or Op Amp output modes and both were measured using the balanced outputs. However, the results were virtually identical, and within the margin of error of the test equipment, so only the Discrete output measurements are presented here.

Our 1 kHz noise spectrum is very quiet, with very small 2nd and 3rd harmonic peaks that are over 110 dB below the fundamental.

With a 10 kHz tone we see a 2nd harmonic that is 100 dB below the fundamental.

On the 60 Hz + 7000 Hz IMD test, the spectrum looks very clean, though the peaks are a bit wider than is ideal.

On the 19000 Hz + 20000 Hz IMD test, we see a very tiny B-A peak that is almost 110 dB below the fundamental tones.

Switching to the unbalanced outputs, we see much different results.

The main thing we notice is a slope from 0 Hz to 3 kHz, as the noise floor goes from -100 dB to -120 dB. Because of this higher noise floor there is more THD+N in this measurement.

With 10 kHz we see the same results as with the balanced outputs, except for the noise floor issue below 3 kHz again.

Again we have the same results as the balanced outputs, except for that noise floor.

Finally, on the 19 kHz + 20 Khz IMD test, the B-A peak we saw with the balanced outputs is likely preset, but obscured by that noise floor issue with the unbalanced outputs.

With the balanced outputs, the Halo CD 1 tests wonderfully, though I found no measurable differences in Discrete and Op Amp modes. With the unbalanced connections, the results were good except for a strange noise floor issue from 0 to 3000 Hz. Because of this I’d recommend using the balanced outputs from the CD 1 if possible.


Conclusions about the Parasound Halo CD 1 Player

I said above that this may be the finest player I have ever heard. I base this not only on the sound but the fact that I was able to listen repeatedly even to discs that used to drive me crazy with edginess and fatigue. Count in this category anything by Portishead or the Cocteau Twins. No longer! This player will have you looking at your CD’s and the used CD racks differently.

It’s hard to know how much the sound benefits from the error correcting methods used in the CD 1 vs the DAC and analog sections but my experiments with the Benchmark DAC2 suggest that the error free data stream is key. If that is the case there are alternatives out there. Naim’s HDX Server also performs multiple reads but I don’t know any details on that. In the computer realm, dbPoweramp is inexpensive software for the PC or mac that attempts to get perfect data by comparing your rip of the CD to others. A good idea to be sure. Seems not quite as powerful as the CD 1’s multiple strategies however and would fail miserably if a particular CD has manufacturing issues. Don’t know if that actually happens but given record companies’ attention to detail and sound quality it seems likely.

Also in the computer realm, there are finally some interesting playback options such Audirvana which can upsample and apply IzoTope dithering. That one is available for Apple only at this point. However the convenience of just inserting a disc and getting good sound is hard to beat at least for those of us used to doing so. This is what Parasound is counting on with this player.

Of course I would like to see more features – the ability to read MP3 discs, or a digital input to take advantage of the DAC with a streaming source would be welcome, but would add cost. With the CD 1, Parasound was on a mission for the best CD sound and they have succeeded.