Full expert review and laboratory test of the Parasound Halo 2.1 Integrated Amplifier/DAC by Australian Hi-Fi Magazine.

The following review consists of a full subjective evaluation of the Parasound Halo Amplifier/DAC written by Greg Borrowman, as published in Australian Hi-Fi Magazine, September/October 2016. At the end of the review is a link to a complete set of independent laboratory tests conducted on the Parasound Halo by Newport Test Labs and a report about those tests written by Steve Holding. The link also downloads the original magazine pages, in pdf format.

The arrival of Parasound’s new ‘Halo’ integrated amplifier came as something as a surprise to this reviewer, because Parasound has not built an integrated amplifier since 1986. This doesn’t mean that founder Richard Schram and designer John Curl have been sitting around doing nothing for thirty years. What happened is that after that first integrated amplifier, the two decided to instead specialise in building separate preamplifiers and power amplifiers… which they’ve done with resounding success, winning dozens of awards and literally hundreds of rave reviews over the decades.

Maybe the reason they decided to build the Halo is that it’s not ‘just’ an integrated amplifier. This new Parasound amp has an on-board digital-to-analogue converter, as well as a subwoofer output with its own variable low-pass crossover network, and a built-in electronic crossover that can be used to tailor the signal at the Halo’s own speaker terminals as well as those at the ‘pre-out’ terminals on the rear panel. It also has home theatre bypass circuitry. Plus it has a high-quality headphone amplifier. So while it’s certainly a two-channel integrated amplifier, it’s one that offers much, much more than you’d expect.

The Equipment
Parasound’s Halo is certainly full-featured. On the analogue side, there are five line-level analogue inputs, four of which are unbalanced (RCA terminals) and one of which can either be balanced (XLR terminals) or unbalanced (RCA terminals)—but not both at the same time… you can only connect one or the other—plus there’s a phono input that handles both moving-coil (MC) and moving-magnet (MM) cartridges—with selectable load (100Ω or 47kΩ) for the moving-coil option. Additionally, there’s a front-panel 3.5mm input so you can connect your phone or portable player.

On the digital side, there are optical (Toslink), coaxial (RCA) and USB (Type B) inputs. The digital inputs route to a 32-bit/384kHz Sabre32 Reference DAC (ES9018K2M). Via optical and coax this DAC can handle PCM 16-bit and 32-bit words at sampling rates of up to 192kHz. Via the USB input it can handle up to 32-bit/384kHz PCM as well as DSD and DoP. Apple users can just plug ‘n play, but Windows users will need to download the free USB driver from Parasound’s website: www.parasound.com.
The Halo also has a home theatre bypass output that outputs the left-channel, right-channel and subwoofer signals without any processing or volume adjustment, plus there’s also a pair of fixed-level Record Outputs, so you could send analogue audio to a recorder of some kind.

The front panel continues a cosmetic theme that has been a constant at Parasound for many years now. The slightly outwardly-curved front panel has a shallow groove running along the bottom that houses most of the tell-tale LED indicators and, in this case, the Power on/off and Mute buttons as well. Also carried over is the symmetrical control layout, though in this case Schram has not achieved perfect symmetry, with four controls at the right of the panel (the input selector, subwoofer level control, balance control and volume control) and only two at the left (bass and treble tone controls). Despite this, a degree of symmetry is achieved because the left side of the panel is also home to the tone control circuit’s on/off button, an infra-red receiver window, a 3.5mm auxiliary input and a 3.5mm headphone output… both of the latter being gold-plated.

The LEDs in the previously-mentioned groove light-up to indicate input selection in the following order: Aux, Line 1, Line 2, Line 3, Line 4, Line 5, Phono, Opt, Coax, USB, Bypass. While I was happy changing inputs using the remote control (which is a nice little unit, about which more in a moment), it felt a little strange changing inputs when using the tiny rotary front-panel control. If Schram likes things to be symmetrical, why not balance the large volume control by using an equal-sized input selector?
The Parasound Halo measures 437×150×413mm (WHD) and weighs-in at a fairly hefty 15kg. It’s available in either black or silver finishes.

As for that remote control, it’s made from plastic, but feels very solid in the hand and comes with illuminated keys, which is a particularly nice touch. Press the ‘illuminate’ button on the remote and the keys glow for a usefully-long ten seconds. Using either of the volume controls on the remote cancels muting, whereas it should really only be cancelled when the ‘up’ volume control is pressed. The remote is powered by two AA batteries which, as supplied, were Toshiba zinc-carbon types. I would recommend that you immediately replace these batteries with high-quality leak-proof alkaline types to avoid damaging the remote control.

Internally, as you’ve probably already guessed from its size and weight, the Halo uses a tried-and-tested Class-A/B bipolar output stage, although the driver stage uses MOSFETs and the input stage uses JFETs. Servo circuitry ensures that d.c. is never present at the output terminals, and there’s also circuitry to prevent the amplifier from accidental short-circuits, excessive current draw and overheating. The heart of the headphone amplifier circuit is a Texas Instruments TPA6120A2, which is a Class-AB current-feedback design that has a very high slew-rate to eliminate odd-order distortion, enable ‘current-on-demand’ at the output so the amplifier responds quickly and linearly without distortion, and gain-independent frequency response to ensure that it delivers full bandwidth at all volume settings.

Parasound says all its amplifiers are designed, engineered and QC-tested after completion in the USA, after being built in Taiwan. In Australia, the Halo comes with a three year warranty and full after-sales support from long-established local distributor Network AV, but Schram is happy for Parasound owners to contact him directly and is renowned for answering every email he gets, which has earned him a well-deserved reputation for providing ‘service second to none.’

As for the thirty-five year background of the company, Parasound was founded by Richard Schram in 1981 and he is still its sole owner and the very prominent ‘public face’ of Parasound, as well as the person who decides what products will be built—and he only builds products that, in his words, are ‘saleable, reliable, and most of all, relevant.’ His lead designer is none other than John Curl, whose reputation was forged by his epoch-making designs for Mark Levinson, back when Levinson actually owned the company that still bears his name (the Mark Levinson JC-2 being perhaps the most famous of his designs). Less well-known is that Curl also has designed mastering recorders for Wilson Audio and Mobile Fidelity as well as a professional audio mixing console for The Grateful Dead.

In Use and Listening Sessions
I used Parasound’s Halo in two different systems. One was a two-channel system using only a single pair of large floor-standing speakers; the other was also a two-channel system, but comprised of small bookshelf speakers and a subwoofer. I used this second system primarily so I could evaluate the Parasound Halo’s crossover circuitry. I appreciated the Halo’s extensive feature set right from the outset. The illuminated blue strip inset into the volume control is easy to see from anywhere in the room, so you instantly know how high the volume is set. The blue illumination that indicates the tone controls are in circuit, and the red illumination that indicates that the muting circuit is active are also great aids to useability. I wasn’t quite so enamoured of the headphone output. Firstly I would certainly have preferred a full-sized 6.5mm ‘phone socket. Secondly, plugging headphones in immediately mutes the loudspeakers, the corollary of which is that unplugging your headphones turns the loudspeakers back on, and if the volume level is set high when you do this, you could potentially damage your loudspeakers. Parasound has deliberately built extra gain (12dB) into the headphone circuit to ensure that this is unlikely to happen.

No matter which of the two systems I used, there was power aplenty available from the Parasound Halo. I dare say you will never—ever!—need more power than the 160-watts per channel available (240-watts per channel if you’re using 4Ω loudspeakers!), no matter what loudspeakers you connect to it. It’s also good, clean, distortion-free power, no matter whether I was listening at background music levels, my ‘standard’ listening levels or cranked right up to ‘party, party’ volume levels. I didn’t even hear so much as a hint of output stage distortion, no matter how hard I listened, and when nothing is playing, either between tracks or between notes, the Halo was totally silent, with no hum or hiss audible at all. In fact; no circuit noise whatsoever.

When using the Halo in my 2.1 set-up, using the internal electronic crossovers to strip the high-frequencies from the signal going to the subwoofer and the low frequencies from the signals going to the main speakers resulted in a huge difference in sound quality, allowing the small two-way speakers I was using as main speakers to perform at their best. Don’t be confused that the crossover controls on the rear panel say ‘Pre Output’ and appear to relate to the two RCA outputs beneath. They do control the signal at these outputs, but they also control the signal sent to the Halo’s own speaker terminals.

I was so successful at improving the sound of my bookshelf speakers that I re-connected my large, three-way floorstanding speakers to the Halo, but continued using the 2.1-channel configuration by using the internal crossover to strip away the very lowest frequencies from them so that they handled only the upper bass, and the subwoofer handled the lowest frequencies. I was rewarded with an instant improvement in the performance of the floorstanders: they delivered far-cleaner, much punchier bass, with improved clarity and with much-reduced distortion at higher listening levels.

Turntable owners will find the Halo’s input stages completely transparent with both MM and MC cartridges, removing the need for an added-cost external phono stage… unless you have a phono cartridge that requires a particularly unusual loading. Phono RIAA equalisation was spot-on, and the dynamics I was able to extract from the LPs I played proved the phono circuit’s overload margin was more than adequate for even the most dynamic audiophile recordings (it later tested at 26dB).

I had the same sonic experience using the digital inputs, no matter whether I was feeding hi-res files over USB or had the Halo connected to the SPDIF digital output of a CD player. Listening to Hein Cooper’s Overflow (from ‘The Art of Escape’) the rhythmic drive of the song was delivered like it was on steroids, with the crisp percussion cracking in like rifle shots and the multi-layered vocals delivered with astounding clarity. Exceptional performance indeed, and so exceptionally good that you won’t be needing an external DAC either and, if you have an older CD player with a digital output, connecting that player’s output to the Halo will result in an immediate improvement in sound quality from all your CDs.

If you do choose to feed the Halo an analogue input—either unbalanced or balanced—you’ll be in for an aural experience, because what the Halo will deliver to its outputs is a faithful replica of whatever you deliver to its inputs… just a louder replica! The Halo delivered Janis Joplin’s Work Me, Lord (from the newly released ‘Little Girl Blue’) with spine-tingling authenticity, by way of example.

The quality of sound from the headphone output is outstandingly good, so if this is your preferred method of listening at home, you’ll be able to dump your external headphone amplifier and simply listen via the Halo. And if you don’t have an external headphone amplifier… well the Halo’s headphone amplifier sounds so good that you won’t need to buy one, no matter what headphones you prefer to use.

The Parasound Halo is an excellent amplifier, but it’s also an excellent phono stage, an excellent headphone amplifier, an excellent DAC and the inclusion of the electronic crossover circuit is a secret weapon that will improve the performance of any loudspeakers you own when you’re also using a subwoofer. No surprise then that I consider the Halo to be outstanding value for money. Indeed Schram was once asked the secret of Parasound’s success, and he replied that it was all down to respect. Specifically, he said: ‘We respect our customers because most of them don’t have trust funds and have to work for their money. So we give them their money’s worth and then some.’ I’d have to echo those words, because with Parasound’s new Halo integrated, you are most definitely ‘getting your money’s worth… and then some.’   # greg borrowman 
Readers interested in a full technical appraisal of the performance of the Parasound Halo Integrated Amplifier/DAC can click HERE, or on the graphic at the right, which will download a pdf of the original review, which includes a full independent LABORATORY TEST, including frequency response and distortion graphs, power output measurements and much more....

Brand: Parasound
Model: Halo
Australian Price: $4,995
Warranty: Three Years
Australian Distributor: Network Audio Visual Pty Ltd

High power, low distortion
Tuneable subwoofer output
Built-in electronic crossover networks
On-board DAC

3.5mm headphone socket
Using headphones turns off speaker output