Congrats team Bottlehead! This is something I could become interested in. I'm curious to the lack of adjustablility in input load both resistive and capacitive. Is it there and I'm just missing it in the description?
We can certainly adjust the load for the client when we build the preamp if they are using a cartridge that has a requirement different than the standard 47K ohms. From what I have seen the manufacturer's recommendations for loads often don't apply that well in the typical setup and to find a value that is going to get the response of the cart significantly flatter than the 47K load gives will require measuring the response curve of the cartridge/cable/phono preamp system and "cutting and trying" resistor values until you find one that's better in your particular system. We sometimes install trim pots in the Tube Repro to allow for different playback heads, and the only way to be sure we have it right is to do these response measurements. As for capacitance, the best thing to do seems to be keeping it very low, which we have accomplished with the use of an EF86 pentode at the input. That's probably the best approach, as capacitive loading seems possibly to be a "cure" for issues that should probably be addressed by resistive loading adjustment - or a different cartridge.
All that said, if someone wants to add shunt capacitance to the signal path on top of what their phono cable already adds we could probably accommodate them. These are after all custom built to order.
