Shut Up And Take My Money

Yeah, its that time again. Same bat time, same bat channel. Another fantastic product from Geshelli Labs. The good news this time for you and your wallet is this is the last amp in Geshelli’s line up. The bad news is it’s just as good as the ENOG 2 DAC, and Archel 2 Pro that we reviewed a few weeks ago. The last time I told you to get your wallets ready. Today though, I’m the one that’s saying shut up and take my money. My custom Geshelli Labs Archel 2.5 Pro is being constructed as we speak, but more on that later.

Geshelli Labs Archel 2.5 Pro Packaging

As always, I start with the unboxing. Geshelli, like before packages their products in nice white boxes proudly displaying the Geshelli name. Inside you will find the Archel 2.5 Pro, the very small power brick, a Geshelli vinal magnet, a cleaning cloth, and a user guide. All of which is well protected by a custom-fitted foam insert. If you are new to Hifi audio this is actually more than you get with most audio products.

The Dark Knight Returns

Let’s move onto the Archel 2.5 itself. If you weren’t reading the name on the front plexiglass you’d be forgiven for confusing the Archel 2.5 for the Archel 2 from the front they look practically identical. The only external physical difference seems to be the Archel 2.5 is deeper front to back. This, in my opinion, is great. That means the ENOG 2 DAC fits perfectly on top as it does with the Archel 2 Pro and if you’re updating from the Archel 2 Pro it will slot right into its place with little trouble.

Geshelli Labs Archel 2.5 Pro at the Bottom, top is the ENOG 2 Pro

If you have not read the Archel 2 Pro review ( What are you waiting on) but seriously though the front is laid out exactly the same.

Left to Right: Power/ LED btn, input/gain btn, 1/4 output, gain indicator LED, Volume Knob.

Front Elements

Moving left to right, the first button is the combination power and LED button. Holding the button down powers the amp on or off. Pressing it cycles through the LED colors. The first color is purple, the second is red, the third color is blue and lastly, you have the option to turn them off if LEDs aren’t for you.

The second button is the combo input selection and gain button. Pressing will swap inputs between the balanced XLR input and the single-ended RCA inputs. You’ve got to love the simplicity of the 2 button setup.

Next, is the metal 1/4 stereo output. I’ve mentioned it before but I feel I can’t mention it enough, many other amps in this price range still use cheaper plastic outputs. Not Geshelli. Metal for the win.

Wrapping up the front elements we have 2 LEDs to the right of the headphone output. These indicate the gain levels, one LED for low gain which is unity gain, or 2 LEDs for high gain which is X6.

The last element is the volume knob which is rather thin a small when compared to other volume knobs. The potentiometer that Geshelli chose feels fantastic though and I found no detectable channel imbalances in my testing. If I had to nitpick anything about the amp physically, I’d like to see a larger knob similar to the Monoprice liquid spark or THX SP200. Again, this is if I have to nitpick something. Not that its a problem I just think it would make a good thing better.

Left to Right: RCA singled ended input, XLR balanced input, Power in

Rear Elements

Working our way to the rear is where things really become interesting. Again starting from the left we have the RCA single-ended inputs. Next to them is the balanced inputs (more on them in a second) and lastly, we have power input.

Before we get too far here are the specs.

Specs

TI 1656 Op Amp Based Design

Impedance 16ohms-600ohms

Audio Taper Potentiometer (A100K

RF Grade Low Noise Regulators

RCA / XLR Inputs (Selectable)

1/4″ Stereo Output

12v FCC Level 6 Power Supply (Included)

LED Control (Red/Blue/Purple/Off)

Gain Switch (Unity Gain or 6x)



Characteristics

< .000095% THD+N @ 2Vrms (RCA)

< .000095% THD+N @ 4Vrms (XLR)

> 120dB SINAD

> 125dB SNR

1 Watt Per Channel @ 16ohms

Ultra Flat Frequency Response



Okay, let’s go back. (I know you’re scratching your head)

Lets Talk About Balance

Yes, Geshelli included a balanced XLR input on the rear but no balanced output. Your eyes haven’t deceived you but before your mind begins to melt ( I can see the gears in your head beginning to grind) allow me to explain.

The first thing I need to explain is if an amp is designed correctly balanced connections aren’t needed and can even decrease the overall sound quality. XLR/Balanced connections separate the ground signal which in the right ( or wrong rather) environment will help or completely remove what is called RF ( radio frequency) noise or ground loops. This is typically a problem that is found where the sound travels long distances or around poorly insulated wires. Here is the kicker, most headphones amps are only inches from the DAC and headphones a few feet from the amp at most. Maybe once upon a time, we needed that extra protection from noise but not anymore in my opinion.

Allow me to go a little further into what the Archel 2.5 Pro is actually doing and a quick comparison to 2 very popular headphone amps. Inside the Archel 2.5 takes the balanced input and processes it through dual independent power supply and performs additional noise rejected in hardware. This results in a clean output free of noise even with sensitive IEM. So while technically not balanced all the benefits of a truly balanced amp are present and even better than some truly balanced amps.

Optional Red Plexi-glass faceplate

Now to my comparison. Even if you are new to the world of premium headphone Hifi there is a large chance that you’ve come across the THX amps. More specifically the Drop 789 and the S.M.S.L SP200 THX 888 amps. Both are super clean headphone amp powerhouse, both have balanced input and balanced outputs… ‘

The More You Know

(Now brace for impact) –Neither of them is truly balanced...

Yep, you read that right, neither is truly balanced. Both amps combine the ground signal in the volume potentiometer and in the case of the 789 its not a particularly good potentiometer.

So now your wondering, well how are people hearing a noticeable difference?

The simple answer, input voltage. The amplifier output can be drastically affected by the signal input voltage of the source. RCA output on most good DAC are going to be around 2 volts while the XLR output on the same DAC is going to be about twice that at 4 volts. Long story short higher input voltage means higher amp output. Combine that higher power with a pair of headphones that really open up with a little extra boost in power and voila! Magic, headphones sound better, they have more resolution, more body, more slam because they were run balanced(#notreally)… Hopefully, you know now that is not the case. The power output was simply increased.

You get a similar effect when using power-hungry headphones on the Archel 2 pro and then swapping to the Archel 2.5 pro that has higher power output.

“Okay, Mr. Smarty Pants. If the THX amps aren’t really balanced what’s the difference when compared to the Archel 2.5 Pro?”

Ahhh Haaaaa!! there isn’t… 0_o

Honesty Is The Best Policy

Geshelli is honest about what they have done, no illusions needed. Feed it an XLR input at 4 volts from a DAC like the ENOG2 and you’ll get the same effect and output that you would from connecting headphones with a balanced cable.

Optional Florescent green face plate

The Man

After talking to Geno Geshelli himself it is possible to see a reduction of noise by running the XLR inputs at higher voltages… for instance, running at 5 volts XLR input VS 4 volts can greatly reduce the noise levels even further. The problem with this though is we’re already talking noise levels below human hearing. So it is redundant to make it even quieter, but he can and likely will for the guys that need to look at graphics to hear how something sounds (chuckling inside). Most importantly though, you wouldn’t need a balance headphone output to see this advantage. Further proving why you really don’t need a balanced output.

The last thing that I’ll mention is the XLR are there as an optional way of connecting a source. Its inclusion on the 2.5 was a no brainer as the ENOG 2 has balanced outputs. Will we see a balanced output on a Geshelli amp, who knows. Time will tell, but if we do it will likely be for convenience as Geshelli has already proven they don’t need it to provide clean, clear, quality sound.

Oh, That Sound!

Let’s get into the real meat of any amp. How it sounds. I can really keep this section brief and to the point. It sounds flipping fantastic. I stated in my review of the Archel 2 that its sound was on par or better than the THX amps that many have been using as a sound quality measuring stick. The same is true for the Geshelli Archel 2.5 Pro. The 2.5 has a similar tonality when compared to the Archel 2, however, the increase in power provides a bit more thump. BUT! (and it’s a big but)

The results above were the results of me using single-ended RCA output from the ENOG 2.

Optional purple Plexi-glass face plate

I also tested using the balanced output from the ENOG 2 to both the Archel 2.5 Pro and THX888 SP200 and things started to get interesting. Keep in mind I did mention that you didn’t need a balanced headphone output to get the benefits of the additional power the (XLR) balance would drive from the amp. This is a perfect example of why the Geshelli really doesn’t need a balanced output.

More Power

Just by swapping the source on either amp from RCA to XLR resulted in an audible increase in sound. This was expected for the reasons I listed above, but what else I heard wasn’t. Listening with the Focal Clear Professional I noticed the sound of the Geshelli Archel 2.5 Pro picked up a richer, fuller sound that remained clean but was noticeably different in a pleasing way.

So what does all this mean? Well…

If your DAC isn’t balanced and you’re using the RCA input you probably couldn’t tell the Archel 2.5 and a THX amp apart at a reasonable listening volume.

If you plan on using the balanced XLR connections and you’re getting 4 volts into to Archel 2.5 you are going to get a richer, lush, full, clean sound.

I found in my testing the Archel 2.5 instantly had more thump on my HE4XX planar and 600 ohm DT880s when compared to the Archel 2. The level of thump was about what I get from the Liquid spark which is about twice the power output of the Gesheslli Labs Archel 2.5. The treble was clear and resolving similar to the THX888. Overall, The Archel 2.5 is transparent. You’ll get out what you put in. Put clean signal in, get clean audio out.

Final Thoughts

My reservation was if you had harder to drive planar or other hard to drive headphones to get the 2.5 over the Archel 2. After spending time with the Geshelli Archel 2.5 that is exactly what you should do. Headphones in the sub 250 Ohm range, and that aren’t hard to drive planar get the Archel 2. If you plan on or have harder to drive headphones like myself get the 2.5.

I’ve put my money where my mouth is. What I’m about to tell you is a bit of a secret. A hidden menu item if you will. The Archel series amps are available in a few colors. The sexy black that I’ve reviewed here, but you can also get a raw silver.

The Archel 2.5 with a few of the optional face plates. Smoked installed. Red, Green, and Purple shown. Clear and Blacked out are also available.

Shh Don’t Tell

What you might not know is Sherri Geshelli has been dabbling with powder coating and has been turning out some sick limited edition units and one-offs. That is right, one-off and limited run colors. If a custom color case isn’t enough for you or you want something a little more subtle and less permanent Geshelli will soon have optional front and rear plexiglass panels. Some of which you can see in the photos.

My Geshelli Labs Archel 2.5 Pro is going to be my own, a work of art if you will. I’ll be posting pictures of it soon, along with some extras that we’re doing to it when it comes in. If you want beautiful sound in a one-off or limit run package then look no further, No one else is doing it… Period.

Headphones That I Used For Testing