This is a review and detailed measurements of the Geshelli Archel2.5 Pro headphone amplifier with XLR balanced inputs (no output). It was kindly sent to me for testing by a member a while ago . It costs US $180 from the company.
The Archel2.5 Pro is typical of Geshelli enclosure with aluminum and plexiglass:
The ones on the website seem to have smoked glass now which I think is a better bet. Wish there was a 3.5mm jack since there seems to be room for it. Controls are microprocessor based requiring long press to change the gain on the input selector.
The back panel is nothing unusual other than aforementioned inclusion of XLR inputs:
Forgot to take a picture of the external power supply but it is very small, not a whole lot bigger than a phone charger. That aspect is nice but the small size also means lower current delivery which can hurt driving low impedance headphones.
Archel2.5 Pro Measurements
I exclusively used the XLR input on this unit. With 4 volts in and 4 volts out, this is what we get:
That is pretty good, just shy of top of the class:
If I turned up the volume a bit more with output at 4.3, SINAD would jump to 120. Alas, that would not be fair to other companies so left it there.
Signal to noise ratio is excellent as well with the same 4 volt out:
Turning the volume down to 50 mv (right), gives us almost top of the class rating again:
So you should be good with your sensitive IEMs.
Frequency response is of course ruler flat:
Most important test is power vs distortion+noise so let's get into that starting with 300 ohm load:
Low gain performance is superb. Alas when you switch to high gain, you loose some of that. Power is healthy at 152 milliwatts before clipping.
Switching to much lower load of 33 ohm shows the issue I talked about regarding lack of current:
Low gain is once more excellent as far as noise and performance but that better be all the power you need (half a watt). Switching to high gain gets you a bit more power but with more distortion and then severe clipping.
Channel matching is a bit worse than I expected with some imbalance early in the range which I don't often see:
As noted though, with all these analog controls what you get may very well be different than what I have/have measured. Still, be on guard with issues regarding very sensitive IEMs.
Geshelli Archtel2.5 Pro Listening Tests
I started testing using the Sennheiser HD-650 headphone. Even in low gain there was plenty of power to produce absolutely clean and dynamic response. Absolutely superb. Switching to high gain though took things to an entirely different level. For the few seconds that I dared to turn up the level to near max, my skull resonated so much (and with such great fidelity) that I think it may have jumbled some of my brain cells, converting me from an engineer to a painter!!!
I then switched to my very inefficient, 25 ohm Ether CX headphone. Up to pretty reasonable volumes the fidelity was excellent. Turned up the volume a bit more and bass notes started to have pops of static. Go a bit more and incredible transformation happens with bass notes getting modulated into some kind of electronicky synthesized tones! It was uncanny as at first I thought it was in the music only realizing that it is not. Again, there was enough volume before this happened but there is a hard limit here as indicated by the 33 ohm measurement above.
Conclusions
The Geshelli Archel2.5 Pro definitely belongs to the new elite class of headphone amplifiers which provide incredible amount of power and transparency at the same time. You are guaranteed to hear what is in the recording, no ifs and buts. For Archtel2.5 this is true of high impedance headphones. With low impedance headphones, you give up some power which the competitors do not. So be mindful of that as you shop.
Overall, I can recommend the Archel2.5 Pro for medium to high impedance headphones.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
The Archel2.5 Pro is typical of Geshelli enclosure with aluminum and plexiglass:
The ones on the website seem to have smoked glass now which I think is a better bet. Wish there was a 3.5mm jack since there seems to be room for it. Controls are microprocessor based requiring long press to change the gain on the input selector.
The back panel is nothing unusual other than aforementioned inclusion of XLR inputs:
Forgot to take a picture of the external power supply but it is very small, not a whole lot bigger than a phone charger. That aspect is nice but the small size also means lower current delivery which can hurt driving low impedance headphones.
Archel2.5 Pro Measurements
I exclusively used the XLR input on this unit. With 4 volts in and 4 volts out, this is what we get:
That is pretty good, just shy of top of the class:
If I turned up the volume a bit more with output at 4.3, SINAD would jump to 120. Alas, that would not be fair to other companies so left it there.
Signal to noise ratio is excellent as well with the same 4 volt out:
Turning the volume down to 50 mv (right), gives us almost top of the class rating again:
So you should be good with your sensitive IEMs.
Frequency response is of course ruler flat:
Most important test is power vs distortion+noise so let's get into that starting with 300 ohm load:
Low gain performance is superb. Alas when you switch to high gain, you loose some of that. Power is healthy at 152 milliwatts before clipping.
Switching to much lower load of 33 ohm shows the issue I talked about regarding lack of current:
Low gain is once more excellent as far as noise and performance but that better be all the power you need (half a watt). Switching to high gain gets you a bit more power but with more distortion and then severe clipping.
Channel matching is a bit worse than I expected with some imbalance early in the range which I don't often see:
As noted though, with all these analog controls what you get may very well be different than what I have/have measured. Still, be on guard with issues regarding very sensitive IEMs.
Geshelli Archtel2.5 Pro Listening Tests
I started testing using the Sennheiser HD-650 headphone. Even in low gain there was plenty of power to produce absolutely clean and dynamic response. Absolutely superb. Switching to high gain though took things to an entirely different level. For the few seconds that I dared to turn up the level to near max, my skull resonated so much (and with such great fidelity) that I think it may have jumbled some of my brain cells, converting me from an engineer to a painter!!!
I then switched to my very inefficient, 25 ohm Ether CX headphone. Up to pretty reasonable volumes the fidelity was excellent. Turned up the volume a bit more and bass notes started to have pops of static. Go a bit more and incredible transformation happens with bass notes getting modulated into some kind of electronicky synthesized tones! It was uncanny as at first I thought it was in the music only realizing that it is not. Again, there was enough volume before this happened but there is a hard limit here as indicated by the 33 ohm measurement above.
Conclusions
The Geshelli Archel2.5 Pro definitely belongs to the new elite class of headphone amplifiers which provide incredible amount of power and transparency at the same time. You are guaranteed to hear what is in the recording, no ifs and buts. For Archtel2.5 this is true of high impedance headphones. With low impedance headphones, you give up some power which the competitors do not. So be mindful of that as you shop.
Overall, I can recommend the Archel2.5 Pro for medium to high impedance headphones.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
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