During the time I’ve been an audio reviewer I can count on one hand the number of integrated amplifiers I’ve reviewed. But I’ve spent more time listening to integrated amplifiers during the last couple of months than I have during my entire career. What precipitated my sudden intimacy with integrated amplifiers? Space, or more accurately, the lack of it.
In my old abode, every system, except my nearfield computer, had speakers on one side of the room and most of the electronics on the other side, which is not an ideal situation for an integrated amplifier. After all, the beauty of an integrated amplifier is that it combines the preamplifier and power amplifier into one unit, which saves space, and the necessary cable connections between the two. However, if using an integrated means you have to use long speaker wires to get from your amp to your speakers, the cost savings and efficiency an integrated offers could be diminished. In my new home (just as in the old one), I have three systems, but two of those, the computer/nearfield and upstairs living room ones, are situated in a way that makes using an integrated amplifier a sensible and less obtrusive option. All told, it was these factors that piqued my interest in integrated amps.
In Issue 255 I reviewed Vinnie Rossi’s revolutionary LIO modular integrated amplifier system. This review will look at the more conventional, yet equally impressive, design from Parasound. The Halo Integrated 2.1 combines a preamplifier with a power amp, phono preamp, DAC, and built-in adjustable crossover to make a device that can handle any current-format digital, line-level analog, or phono input.
The Parasound Halo integrated amplifier looks very much like other components in the Halo line with its distinctive faceplate sporting a horizontal half-circle cutout running parallel with the base. And like other Halo products, the circuits inside are based on John Curl’s design. According to Parasound’s sales literature, the Halo Integrated offers “the same performance as Halo separates.” The preamplifier section is based on the Parasound P 5, but includes an analog crossover that is similar to, but more flexible than, the crossover in Parasound’s P 7 multichannel preamplifier. The Integrated 2.1’s power amplifier section is similar to the Parasound’s two Class A/AB amplifiers, the A 21 and A 23, but its power rating puts it right between the two separate power amps. The A 23 produces 125 watts into eight ohms, the A 21 puts out 250 watts into eight ohms, and the Halo Integrated is capable of 160 watts into 8 ohms. In theory, a Parasound Halo Integrated 2.1 will produce more power than a P 5/A 23 combo, offer equivalent sound, and deliver more features over the P 5/A 23 for the additional $500 upcharge.
According to Richard Schram, Parasound’s founder and president, “We went to great lengths to eliminate power supply contamination that compromises audio purity in some of the most expensive high-power integrated amps.” The Integrated 2.1 has a dual-mono power supply with an oversized toroidal power transformer and 40,000uF filter capacitance. The power amplifier section employs JFET inputs, MOSFET drivers and twelve high-voltage and high-current bipolar output transistors.
The preamplifier section offers 10dB of gain that can be controlled either from the large front-panel volume knob or the supplied remote. Inputs include five pairs of single-ended RCA line-level analog inputs, one XLR balanced line-level input, one pair of RCA single-ended phono inputs (with built-in phono preamplifier with RIAA curve), and three digital inputs for USB, coaxial SPDIF, and TosLink. In addition to all these inputs, the Integrated 2.1 has one stereo miniplug input on the front panel located beside its headphone output connection. The preamplifier also has treble and bass controls (and a tone-control bypass switch), a balance control, and adjustable crossover settings, which are accessed from the rear panel.
The Integrated 2.1’s crossover is completely analog, and unlike the built-in crossover in the Parasound P 7, the Integrated 2.1’s crossover has separate setting controls for the sub output and the mains output so you can independently set the sub and mains for any crossover point from 20Hz to 140Hz. This additional flexibility can make the difference between a system that integrates seamlessly from subwoofer to main speakers and one that has too much or too little midbass.
The DAC section uses the ESS Sabre32 reference DAC chipset. It is capable of decoding any PCM sources up to 384/32 and DSD 64 (1x), DSD 128 (2x), DSD 256 (4x) native or 384kHz DoP protocols. The RCA SPDIF input is limited to 192/24 as is the TosLink input, but the USB input supports anything commercially available up to 384/32 via USB 2.0, which works natively with the Mac OS (Parasound has a driver available for Windows PCs).
The Halo Integrated phonostage has three settings. The setting switch is on the back panel and offers one moving-magnet as well as two moving-coil settings at either 100 ohms or 47k ohms resistance.
Outputs on the Parasound Integrated 2.1 include one pair of speaker outputs via 24k-gold-plated five-way binding posts, one pair of RCA single-ended fixed “rec out” line-level outputs, one pair of balanced XLR main outputs and a single XLR sub volume-controlled output, two single-ended RCA subwoofer outputs managed by the crossover, and one pair of single-ended RCA main outputs managed by the crossover. So while there is only one pair of speaker outputs, you can easily attach a second or even a third power amplifier to either the balanced or single-ended main outputs to add another set of speakers to a second or third room. Also, you can have more than one subwoofer (but not stereo subs unless you use the main line-level output into an external crossover).
If you plan to incorporate the Halo Integrated into a home-theater system it has provisions for accepting the pre-outs of any home-theater receiver and routing them directly to the power amplifier section of the Halo. This feature, called “home-theater bypass,” can also route your receiver’s subwoofer output so that you won’t need to run two connections to your subwoofer to have it active for both two-channel music and multichannel sources. You can use the Halo to drive the left and right front channels of your system while the receiver handles the center, rear, sub, and side channels (if you have side channels).
Setup and Ergonomics
Installing the Parasound Halo Integrated 2.1 in my upstairs system was easy. I simply removed my Parasound P 7 preamp and Perreaux E110 power amplifier and put the Integrated 2.1 in their places. I’ve been using the Parasound P 7 as my reference preamplifier for several years. In fact, I have two, so that I can have a P 7 in each of my room-based systems. Since the upstairs system was already set up for 2.1 listening with a pair of Skiing Ninja-modified AV123 X-Static speakers and a Velodyne DD+10 subwoofer, inserting the Integrated 2.1 was merely a matter of reconnecting inputs and outputs and then spending some time dialing in the integrated’s built-in crossover.
Setting up the Halo Integrated 2.1’s crossover was relatively easy, but you need to have access to the crossover controls located on the back of the unit. This means that unless you have a setup where you can easily access the rear panel and, ideally, see the crossover controls, you may be doing a lot of hunting and pecking. The knobs are small and there are no detents to alert you to where they’re pointed. Compared with the Parasound P 7 that has crossover controls located in a menu you can access through the remote and see on the front panel, the 2.1’s crossover is not as easy to use, but it does allow for more settings since the P 7 only permits a limited number of crossover options.
When I moved the Halo Integrated 2.1 into my computer audio system the installation was equally simple and straightforward. The primary difference was that I needed to reset the crossover settings for the Audience 1+1 speakers and Aperion Bravus 8D subwoofer.
The Halo runs warm, but not hot. Even when on continuously, it never required a fan or additional ventilation. While I would not recommend shoehorning it into a spot with no ventilation, if you give the unit several inches of breathing room above it, heat build-up should not be an issue.
The remote control for the Halo Integrated 2.1 is plastic with illuminated buttons. It includes volume control, input selection, tone on/off, mute, and power on/off. During the review period, the remote worked reliably.
In day-to-day use, the primary ergonomic feature I missed when compared to the Parasound P 7 was the output level display. Although the Halo Integrated has a fully adjustable, remotely activated volume control, and you can see where the volume has been set via the light on its knob, there is no way to quickly, reliably, and repeatedly match volume levels since the dial is not numerically quantified like the P 7’s. On the plus side, I wish every preamp had the red light on the Mute button just below the Halo Integrated’s volume control; it’s a lot nicer than having to hit the mute button twice to make sure that the mute is not on.
The first system I installed the Halo Integrated into was my upstairs home theater. At first I was surprised to find that the overall soundstage had shrunk somewhat, but after several weeks of operation, once I removed the Halo Integrated from the system and reinstalled P 7/E110 combo, I came to realize that the Halo Integrated now produced a soundstage that was slightly bigger than that of the P 7/E110 combo. Since nothing else had changed in the system, the most likely explanation is that the Halo Integrated needed some break-in time to sound its best.
Right out of the box, the Halo Integrated’s lateral imaging was tight with good specificity, but its depth rendition required some burn-in and playing time before it reached its full potential. Once the unit burned in (for several weeks), I was impressed by its imaging precision and its ability to layer the instruments on my live Boulder Philharmonic concert recordings. I was also aware, from the first time I heard the Halo Integrated, that its power amplifier was, well, powerful. Even on my most dynamic material the Halo had sufficient juice to deliver dynamics with an effortlessness that is the hallmark of a robust yet sophisticated design.
The overall harmonic balance of the Halo Integrated was spot-on. If you need warmish or coolish electronics to bring your speakers or room into a more neutral balance, this component won’t be the answer. Its “straight, no-chaser” approach is ideally suited to speakers and rooms that don’t want or need a push away from neutrality to correct for intrinsic imbalances. And because the Halo does have tone controls, on worst-case recordings I could, and very occasionally did, utilize them to produce more sonically palatable results. There was a slight loss of transparency as a sonic penalty for engaging the tone controls. (You could hear this by merely switching in the controls, even when they were set to flat.) But on the recordings that benefited the most from tonal adjustments the slight loss of transparency from engaging the tone controls was trumped by the gains in harmonic acceptability.
Bass through the Halo Integrated was tight, fast, and well controlled. Although most of my listening was done with a subwoofer, and with the Halo’s subwoofer crossover engaged, the bass remained smooth through the crossover region regardless of which system the unit was placed in. It was easy to achieve seamless integration between the subwoofer and main speakers without any lumpiness or holes in the frequency response. When I ran sinewave sweeps using AudioTest on a MacPro desktop, my B&K SPL meter placed at my nearfield listening position stayed within a 5dB window from 35 to 300Hz.
The last system I had in my computer audio setup was built around the NuPrime DAC-10 DAC/Pre and ST-10 power amplifier. The Halo Integrated’s midrange presentation had more in common with the NuPrime combo than I expected. Both did a superb job of retaining detail and giving music a presence and weight that with the right recordings could produce a stunning sense of immediacy. On “Walk Away” from the new Steel Wheels album No More Rain, the Halo made it easy to separate the vocals from the similarly pitched fiddle played behind them, without making the violin sound etched or overly highlighted.
Upper frequencies through the Halo retained their airiness while avoiding sounding tipped-up or overly emphasized. On my own DSD 128 recordings, the Halo wasn’t fazed even during the most punishing fff passages where amplifiers are most likely to falter. Again, I ran sinewave sweep tests with AudioTest, which confirmed how well the Halo controlled upper frequencies through both the Audience 1+1 and ATC SCM 7 II speakers. In both cases, the upper midrange and treble stayed within a 4dB window at listening position from 1kHz to 13kHz.
Speaking of listening positions, when you consider that the Halo Integrated’s headphone amp has no provisions for headphone gain adjustments, it mated well with a surprisingly wide range of cans. The first headphone I tried was the AKG K-7xx. These mated nicely with the Halo—no hiss or hum even when the volume was turned up to max. The AKG’s sensitivity was also a good match with the Parasound’s headphone amplifier—for most commercial releases the volume settings were between 9 and 12 o’clock. With a more difficult to drive headphone, such as the Beyer Dynamic DT-990 600-ohm version, I had to turn the volume up, but the Halo Integrated’s headphone amp still had plenty of additional unused travel left on its volume knob.
If your only pair of high-performance headphones is a high-sensitivity in-ear monitor such as the Westone ES-5, you will find that the Halo’s headphone amp will produce some low-level hiss and 120Hz hum even with the volume controls turned all the way down. While that hum is not as loud with the ES-5 in-ears as I’ve heard from many fixed-gain headphone preamps, during quiet passages the base noise level was sufficient to affect low-level detail retrieval. With the Jerry Harvey Roxanne’s custom in-ear monitors there was no hiss, only a low-level 120/240Hz hum that was almost low enough to disappear when music was playing.
Late in the review period, I compared the Halo Integrated’s USB/DAC with that in the NuPrime DAC-10. Using Roon as a source, I could not reliably tell a difference between the DAC-10 and the Halo in matched-level comparisons. When I used my own DSD recordings I felt that the DAC-10 had a slight edge. It produced a larger soundstage with better-illuminated inner details and superior separation between instruments in the mix. The differences between the two units were subtle enough that even on hi-res commercial releases they were difficult to detect, and on several A/B tests I could not discern them at all.
I suspect that many audiophiles who never anticipated wanting or needing an integrated amplifier may find, someday, that they do need a compact yet powerful one. If that is the case, they may find that the Parasound Halo Integrated 2.1 amplifier is the high-value solution. For $2495 it includes a powerful basic amplifier coupled to an excellent preamplifier that includes a built-in analog crossover as well as a DAC that supports all modern formats.
Combine the Halo Integrated with a comparable set of speakers, such as the wonderful Audience 1+1, and a good subwoofer like the Velodyne DD10+, and you have the basic building blocks for a glorious-sounding small-room or nearfield system for around $7k. And while I wouldn’t call this an entry-level system, I’d hazard to guess that for many audiophiles, including myself, such a mid-priced system can deliver a high enough level of sonic excellence to make for a joyous listening experience for many years to come.
SPECS & PRICING
Power output: 160Wpc (8 ohms); 240Wpc (4 ohms)
Current capacity: 45 amps peak per channel
Frequency response: 10Hz–100kHz, +0/-3dB
THD: < 0.01%, average listening levels ; < 0.05% at 160W into 8 ohms
SNR (IHF A-weighted): – 103dB (input shorted), line-in; -106 dB, digital-in
Damping factor: > 800 at 20Hz
Max output unbalanced: 7V
Max output balanced: 9V
Phonostage gain/input impedance: 35dB /47k, mm; 52dB /100 or 47k, mc
Crossover slopes: 12dB per octave
Supported DAC sampling rates: USB, up to 384kHz/32-bit PCM, DSD 64, DSD 128, DSD 256, DSD over PCM (DoP) at 384kHz; coax/optical, up to 192kHz/24-bit PCM
DAC: ESS Sabre32 Reference ES9018K2M
Dimensions: 17 1/4″ x 5 7/8″ x 16 1/4″
Weight: 33 lbs.
PARASOUND PRODUCTS, INC.
2250 McKinnon Avenue
San Francisco, CA 94124
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