Geshelli Labs J3 DAC
Tip #111
Dick Olsher (November 2025)

Geshelli Labs is rather unique in that it’s a family affair run by Geno and Sherri Geshelli, and even daughter Rachel can be found on YouTube describing how to perform op amp rolling. There were two main reasons that convinced me to pick up a used J3 some months ago (https://geshelli.com/product/jnog3/), and one of them was the ability to roll in various high-end discrete op amps. The other was the AKM DAC chip. I became a convert via the Gustard A26 which is based around a pair of the new AK4499EX/AK4191 converters. While the J3 still uses the older, pre AKM-factory-fire AK4493, I don’t think that it gives up much in terms of sonic quality. Both of these chips deploy sophisticated sigma-delta architecture to generate a 7-bit high frequency bit stream that is converted to analog using a switched resistor network. Both the Gustard A26 and J3 are capable of exquisite detail resolution that blew away my Denafrips Terminator DAC in this regard.

My J3 came outfitted with two Sparkos 2590 stacked pair op amps with Pro to Dual DIP8 adapters, as well as a pair of Burson V7 Vivid op amps. I later picked up a dual Staccato Audio op amp from VTV Amplifier, which is designed around discrete JFETs and is biased hot at 60 mA. In case you’re wondering, at least in this context, I found the Sparkos to be too laid back and lacking in dynamic drive. The Burson V7 Vivid was more forward sounding than the Sparkos and projected sweeter midrange textures than the Staccato Audio. Overall, the Staccato Audio in the Coax input position was more neutral tonally and capable of cleaner macrodynamics. On most musical selections I found the Staccato Audio op amp to deliver a more rounded performance, especially when driven with the battery power supply.

It has been my experience that the power supply is responsible for a big slice of the sonic pie when it comes to DAC design, the actual chip set used contributing only a fraction to the total. I’m not a fan of switching-mode wall-wart power supplies. So the stock wall-wart was quickly replaced by a 12VDC linear power supply. It made for an immediate improvement, smoothing out musical textures, expanding soundstage dimensions, and improving image focus. It took a while, a few months to be exact, for the switch to a Lithium Iron Phosphate Battery rated at 22 Ah and 12.8VDC. It uses 4 cells wired in series, each providing 3.2 VDC. Yes, ZapLitho (cool name) is a Chinese brand that I sourced off Amazon for a reasonable price. Fully charged the voltage measured 13.4VDC and settled at 13.1VDC after a couple of hours of use. Its built-in voltage display is quite useful for confirming battery status. I’m estimating about 100 hours between charging cycles. However, I found it necessary to disconnect the power cable after each use, or else the battery would discharge quite rapidly to 10VDC in 24 hours. The battery is connected to the J3 via a 1-meter long 22-gauge cable, terminated with a 5.5mm x 2.5mm barrel male plug and bare wire at the battery terminals.

To be honest, I didn’t expect the battery to make for a dramatic leap in sonic quality. But it did, quite stunning actually. Not only did the noise floor drop, but soundstage transparency increased significantly, as did image focus and 3D palpability. Tonal colors were spot on and low-level detail became easier to resolve. And even more crucial was the enhanced emotional connection with the music’s passion. For an investment of about $60 the J3 was catapulted to the exalted status of my favorite DAC in the under $2K category. If you go down this road, you will also want to invest in a suitable battery charger such as a CTEK smart Lithium charger.