Amplifier
SRP: $995
Features:
Class A power amp
Drives any headphones
USB input plus analog (RCA) inputs
Gain Cell driven
Front panel knob controls gain
Huge toroidal power supply
Feed from your preamp or computer
Low noise
Built in drivers for any computer
Detachable AC cord
Dimensions: 14″ L x 8.5″ W x 2.5″ H
PS Audio
4826 Sterling Drive
Boulder, CO 80301
720-406-8946
service@psaudio.com
www.psaudio.com
Intro
The rather specialized area of dedicated headphone amplifiers seems to be receiving more attention lately due to the rapidly expanding number of users who do most of their music listening either at their computer or via their iPod or similar mobile device. The headphone output from the sound card of most computers is very poor, just as is the output from the headphone jack present on most preamps and receivers (those that even deign to include them today). After upgrading to high end headphones (which for me start with the $60 Grados), the next step to further improvement of headphone sonics is a dedicated amp.
Setup for Analog Audio In
As you can see by the dimensions of the GCHA, this is not going to be a unit with which you power the high-end phones you got for your iPod – unless you use the iPod at your desk. It’s not even one you probably will be taking from room to room of your house, but installing either next to your computer or close to your main seating in front of your audio or AV system. The goal of PS Audio’s engineers in their very first headphone amp was to create a produce enabling customers to experience high-end audio anywhere they had a computer or stereo system.
I set up the GCHA first near my sweet spot on the sofa and ran a Jena Labs stereo cable over to the output on my Sunfire Theater Grand IV. I tested it with both Grado and Sennheiser phones. I was disappointed I was unable to find a proper adaptor to try it with my favorite headphones – the AKG K-1000s, which come with an XLR connection. I was also disappointed that there was only a single phone-plug-size jack on the GCHA. One can of course use a simple Y-adaptor from any Radio Shack for dual headphone listening, but it seems to me that an amp at this price level should have two headphone jacks.
The AKGs require much more driving force than standard headphones though they are dynamic. I wouldn’t normally have considered trying to use them, but the range of level with the Gain control on the PS Audio amp was so tremendously wide with my Grados that I surmised there might be enough output to excite the AKGs. (Although the amp is only a couple watts.) The GCHA doesn’t employ a normal level control. Instead, its unique Gain Cell allows for adjustable gain without any attention of the signal as normal level controls do. The gain of the discrete Class A amp is itself adjusted to match your headphones and listening needs – instead of running full blast and having an attenuation damp it down. The Gain control also has an on-off setting, but PA Audio suggests leaving the amp on at all times. I left it on for a couple days before beginning the listening tests.
Analog Audio Auditioning
The GCHA has a completely silent noise floor when hooked up properly and feeding normal levels to your phones. At first I was hearing a barely audible buzz, but lifting the AC ground on the hefty line cord immediately corrected that. I also hooked up my reference headphone amp, the dedicated amp for the AKG K-1000 phones, which I understand is not currently available. (When it was it retailed for a few hundred dollars more than the GCHA.) I auditioned first the stereo SACD option of a new BIS recording of Tchaikovsky’s First Symphony. The sonics were rich and detailed. I don’t believe I had listened to many stereo SACDs on phones and found that I may be doing that more frequently in reviewing discs after this – the contrasts with the CD layer are emphasized with headphones versus speaker listening. The two amps sounded almost alike with the Grados.
I next moved to a couple of true binaural CDs. One is a no-longer-available demo disc from Germany’s Audio magazine. It has a variety of music and sound effect demos. Then I listened to a DVD-R of a binaural recording I had made myself of a piano duo at the Maybeck Recital Hall in Berkeley, California – where Concord recorded a lengthy series of solo albums by top jazz pianists. I had placed my dummy head directly between the two grand pianos which had their lids up. This is two-piano jazz like you’ve never heard before!
With these sources I was able to discern a subtle difference between the two dedicated amps. The AKG provided a modicum of better transparency and separation between the two pianos, but only by a minimal amount. It has a smaller power supply than the huge one that makes the PS Audio unit so large and heavy, but it is remoted from the amp by a cable of some length. I wondered if that couldn’t be a factor here. However, both amps continued to provide a superb signal to my phones.
USB Connection Auditioning
Moving the GCHA to my office I placed it on the desk next to my 20″ iMac and connected the provided USB cable between them. At first I could get no sound, and no drivers came up on my screen. But then I remembered the Sound settings in System Preferences and switched the output to Digital Out. It then displayed “Burr-Brown Processor, Japan.” and I had a signal on the headphones. There is no requirement for installing any software and no CD-ROM is provided with the GCHA. I had to raise the Gain quite a bit over the setting I had with my audio system.
It was now New Year’s Eve, so I listened to the NPR live music program from various venues around the country. I was impressed with the excellent sound, especially the bass end which is practically nonexistent when just plugging phones into the mini jack on the rear of the iMac G5. In fact I noticed a couple times the deep bass tone which NPR uses to cue various equipment; something I had never noticed when listening on speakers. I also auditioned some CDs which I was in the process of reviewing. They were an improvement over the radio broadcast, as expected, and it was a pleasure to have instant control over the level with the physical Gain knob on the GCHA instead of struggling with the tiny slider button on the screen of my iMac. (Of course one advantage of phones is that when the phone rings you don’t need to lower the volume – just take them off your ears!)
Since I didn’t have the AKG amp at hand to do a comparison in the office, I decided to compare the USB feed with an analog connection to the iMac. I had recently discovered with the Onkyo D-A processor I use with the iMac that a simple analog connection from the iMac thru Line In on the Onkyo and then to my amp and speakers, provided a bit better sound and a higher gain than I got with the optical digital cable connection I had been using. Now I just moved the pair of RCA plugs from the end of the analog patch cord from the Onkyo to the inputs of the GCHA. What I heard was similar to the improvement I had realized with the Onkyo: the analog connection provided a bit more transparency and clarity than the USB. And this was a very basic short Radio Shack cable too.
I should mention that I didn’t install some of the enhancements suggested in the PS Audio manual: I didn’t try one of my Kimber AC cables with the GCHA. I did not plug it into my PS Audio Ultimate Outlet, which they suggest. And I didn’t set it up properly on an equipment shelf with isolator feet underneath and perhaps a weight on top. Such tweaks could possible elevate the slight discrepancy with my reference headphone phone so that both units matched perfectly. All in all the GCHA is a successful high end headphone amp which is easily available now, and if you have the space and budget for it should certainly be considered in your effort to upgrade your headphone listening experience.
– John Sunier
