The GCHA is a very solid amp both physically and sonically. The amp shares the same housing as the DLIII DAC and sits on top of the DLIII perfectly. The GCHA looks very nice on a desktop with the single blue LED and the appropriately sized volume control. One note about the volume control is that it's very smooth and rich feeling as opposed to similar units with detents for every few db. The amp has both balanced and single ended analog inputs as well as a USB input. The USB input and built-in DAC are very nice for listeners who want a single chassis unit and allows listeners the chance to get their feet wet with computer based audio if they haven't already. This headphone amp is just right for people who don't need a lot of bells and whistles and don't want to pay for features they'll never use. Priced at just under a thousand US dollars this headphone amp should be in the sweet spot for many readers. The Duet Power Center is small but built like a rock. It has to be the heaviest four pounds I've ever lifted. If you don't have perfect power this could be the best three hundred bucks you've ever spent.
I gave the GCHA amp several workouts over the course of many weeks. All the music I threw at it came back to me sounding really good. My favorite music through this amp was good old rock and roll. I scrolled over to the Stones' Bridges to Babylon with my RS-1s on and cranked Anybody Seen My Baby a few times over the course of the review. I also got into the debut album from Rage Against the Machine. The GCHA was very solid even at very high volumes. The bass in Know Your Enemy can really stress an amplifier and turn a good one bad in no time. Fortunately this amp breezed through this track and the rest of the album without sweating.
In addition to my RS-1s I listened for quite some time with my Sennheiser HD600 headphones. This combination may not be for everyone, but will certainly be right up some readers' alleys. To me the sound was all business. Black background, with the help of the Duet Power Center, and very matter of fact sounding. Some may consider this dry or dark while others consider this dead-accurate without any warmth. One huge benefit of a really nice headphone amp is the ability to change headphones, without the cost of a new pair of speakers, to enjoy a totally different sound. If you're one of the few out there, like me, who also use very sensitive earphones like Ultimate Ears ue11 Pros while listening at your desktop, you'll want to give this amp a listen to make sure it fits your needs. In a very limited set of circumstances there may be a slight audible hum when using earphones like the ue11s. Most people will never run in to this, but I think it is worth mentioning here.
Going back to my music of choice during this review, you may think a silent background really doesn't matter all that much. Blasting Rage Against The Machine with a little garbage in the AC line may be OK for some readers, but I just can't deal with it. Nothing detracts more from a great listening experience than hearing squeals during the quiet passages of an album. Even if it's in between tracks it still bugs the heck out of me. This is where the Duet Power Center can really make a nice difference. I know many readers probably wear headphones while using their computers, I certainly do. In most situations computers and monitors and routers and external disks must be plugged in pretty close to your headphone amp. You can't do much worse than sharing your power between these devices and your audio components. The Duet is a perfect product for this type of situation. It's small enough for any office or computer desk and will isolate your gear like no other product in its price range. In addition plugging your monitor into one of the IsoZones will insure you're getting the most out of that monitor you spent several hundred dollars on. There is nothing like plugging your $1800 Apple 30" Cinema Display into an unfiltered and unprotected wall outlet! I even tried my TV with this thing and I can attest to seeing the difference without even trying. I also put the Duet to the test another way. I have a very bad wallwart power supply from an unrelated piece of gear. This wallwart puts noise back in to the AC line like nobody's business. So, I plugged it in to the Duet right next to the GCHA headphone amp and waited for the squealing to start. To be honest, I'm still waiting! Since the Duet comes from a long lineage of really good power products I got just what I expected. A piece of gear that works great and can take anything you throw its way.
More on the GCHA headphone amp. As I said earlier the built-in USB DAC is a really nice feature. However, I've been spoiled lately listening through the DLIII so I had to give it a shot connected to the GCHA. As soon as I clicked over to the new output in OS X Audio Midi Setup I noticed a fabulous improvement. The DLIII is a dedicated DAC so the performance improvement better be this significant or PS Audio would have some explaining to do! Once I had this configuration rolling I couldn't go back. For those of you who already own the GCHA you cant afford not to throw a DLIII into the mix and elevate your game to the next level. Don't get me wrong the GCHA is very good by itself, but the sonic improvement of the external DAC is unmistakeable.
The GCHA by itself is a great value as is the DLIII. Combine these two, plus a Duet for clean protected power, and the GCHA's performance is elevated from terrific to transparent.