Set up for ZU103 cart and K&K SUT

I agree with both of the posts above. Doug's first point hits the nail on the head: why do you need a step up at all? I hadn't looked up the specs for your phono stage, but now I have. Your GPCH has several different gain settings and different cartridge load settings. The 100 ohm load setting is right in the middle of Zu's recommended range; just use that. And you can easily select the best gain level for your system. You have up to 66 db gain, which is enough for even a passive set up. Your phono stage eliminates any need for a step up transformer.

I owned one of these and was a bit confused, too -- it's a quagmire for the uninitiated. But the ONE thing to read is right on Kevin's web site, http://www.kandkaudio.com/mccartsetup.html. I had to read it several times. I'm slow. The goal is to configure the step up transformer for (a) the desired amount of gain and (b) optimum cartridge loading. I looked up the specs for your cartridge an the recommended resistive load is 80-150 ohms.

Following the example in Kevin's article, with your step up the transformer set up for a gain factor of 8x, your cartridge would "see" a load impedance of approximately 734 ohms, which is arrived at by dividing the phono stage's input resistor setting (47,000) by the step up transformer's impedance ratio (64). To achieve optimum loading, you would need to add a parallel resistor in one of the values shown in the chart in Kevin's article. For a resistive load of 150 ohms, use a parallel resistor with a value of 15300 ohms. You can buy them at Radio Shack; they're inexpensive.

But: when you add a parallel resistor, it will reduce the effective gain from the transformer, significantly. My suggestion would be to try the step up as configured now, with an 8x gain factor, and use a 15300 ohm parallel resistor to bring the cartridge loading into the manufacturer's recommended range. Listen, and if you have enough gain, great. If not, then you'll need to reconfigure the transformer for a 16x gain factor. Hope this helps.