Well, I was able to add a jumper (it's not pretty but it works) and now my Piccolo has a zero gain setting. I wanted the zero gain to see if it would help in further reducing noise (sounds like wind across a microphone). Following are the results of my experiment, though the solution was not what I was trying to accomplish with the zero gain setting.
I use the Piccolo headamp as a means to have additional loading options for a LOMC cartridge. The Rogue Audio Stealth phono preamp that I use has sufficient gain for a Dynavector DV-20XL (0.3 mV output) cartridge but lacks the ability to load a cartridge below 100 Ohms of resistance. The Piccolo does a nice job of providing the additional loading but I have been trying to reduce the noise at higher volume levels of around 90 dB peaks. The Stealth is dead quiet on its own and the Piccolo is also dead quiet on its own but when you put the two together (in my system anyway) there is some noise during quiet passages at louder listening levels. I've tried reducing the noise levels by changing interconnects, moving the Piccolo around (reasonable distances), even tried several grounding schemes but I haven't been able to make much of a difference. The noise levels aren't bad, just something I've wanted to fix or at least reduce.
I've been running the Stealth at 50 dB of gain and the Piccolo at 12 dB of gain (the stock minimum setting) for a total gain of 62 dB. It's a good range for my integrated amp. So I wanted to try running the Stealth at 60/65 dB of gain and the Piccolo at zero to see if there was a reduction in noise levels. My thinking was that since the Piccolo was introducing noise into the system, I'd drop its gain to zero and rely on the quiet gain from the Stealth.
The results were not what I expected. The noise levels actually increased with this configuration. (Many of you are thinking "Duh".)
The Stealth was amplifying the noise coming from the Piccolo. So, I tried just the opposite; I set the Stealth to its lowest gain of 40 dB and ran the Piccolo at 20/26 dB of gain and the noise was dramatically reduced. This was counterintuitive to me and I still don't really know what's going on but it works and I'm a happy camper.
I post this in case anyone else has been trying to reduce noise levels using a headamp and weren't getting anywhere using the same logic I used. And for any of you electronics experts, I'd enjoy hearing what you think might be going on. Perhaps there's a different solution or one that cumulatively could reduce noise levels even further.
Tom
PS: Once again, I heartily recommend the Piccolo. The ability to easily set gain, the wide range of resistance settings (even custom values if requested), and the convenience of on-the-fly cartridge loading is a nice feature of this headamp.
