Wow there's so few threads here at head-fi on the Furutech ADL GT40. Just got myself the GT40 New Old Stock (NOS) for just $250 from a local retailer when I tried to buy an integrated Amp-DAC that has USB connection.
My goal was to play FLAC files from my laptop and at that time I came up with two choices that were available here at Jakarta, Indonesia:
1. Centrance Dacport (sold by store A)
2. Furutech ADL GT40 (sold by store B)
*Please note that my Headphone is Senn HD600
Intially I was very impressed by the Centrance Dacport because of the size (portability) and power. I've tested the Dacport connected to a laptop playing FLACs via Foobar2000 using a Beyer T1 and Senn Momentum Over Ear. The Dacport did not broke any sweat when driving the momentum, the power was too much for me when hearing the Momentum. After that I switched to the T1 and all become much more balanced.
Tested a few tracks from Eric Clapton, Santana, and Michael Buble, I've noticed that the Dacport has so much energy and detail. The mids were thick and dynamic. The highs were quite extended and it seemed that there were no details being lost. The lows were also full but at times could overlap the mids. Soundstage was huge and in your face.
After some short critical listening, I've noted that the with so much energy being presented by the Dacport, it cannot present a very clear separation of vocal & instruments. All the sounds seemed to be mashed up in one huge image. I imagined that I cannot listen to this sound signature for a long period period of time because it would not be enjoyable.
I've read several reviews of the Dacport here and most of the feedbacks were positive. Honestly I would give two thumbs up for a device so small and with so much energy/dynamics but I do not think it will suit my taste as I would like to have a more relaxed presentation. Furthermore, the Dacport is limited to only USB connection and THAT'S IT. It does not have any further input/output option that I may need in the future.
Now coming to the GT40...
At the local retailer, I auditioned the GT40 using Senn HD800 (at that moment, the store did not have a Senn HD600/650 ready for demo) and an Audeze LCD 2.
At first, using the HD800, I've noticed that the presentation of the GT40 was more laid back than the Dacport. The sound was not as in-your-face as the Dacport. The sound signature was neutral with a touch of warmth, which I imagined would be suitable for my HD600. The separation was more apparent with the GT40 than the Dacport. The soundstage was not as big as the Dacport but just right for my taste.
Switching to the LCD 2, wow I immediately fell in love with the Audeze! (never heard it before). The basic signature of the amp was still apparent, but I was more struck by the difference characteristics between the headphones. I guess I don't have to explain the difference of characteristics between the HD800 and LCD 2.
After some careful thinking, I went home with the GT40. Having used the GT40 for about 200-300 hours now with my Senn HD600, I have come to the conclusion that I was right choosing this amp. It is neutral with a touch of warmth, good seperation, have sufficient dynamic/energy (it's not the quickest amp out there), sweet sounding and it has many input/output options.
Overall, for the price I've paid for it or maybe for an amp under $500, this should be everyone's consideration.
I would love to know any other experiences about the GT40 from everyone here