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).