A + plus for battery power! I have a Marcof PPA-1 head amp with battery power for use with LOMC cartridges. One advantage a SS gain stage has over a transformer is extended bandwidth.
Yamamoto HSA-01 headshell/head amp
During my recent trip to Tokyo, I happened upon this gadget. It is a headshell with a built-in gain stage that boosts signal voltage in the ratio 1:14. Apparently this is achieved via a tiny op amp and battery power, both seated in the base of the headshell, behind the phono cartridge mounting area. The beauty of the idea is you can thus boost the signal of a very low output LOMC right at its source, before it has had to travel over connectors, tonearm wires, more connectors, etc, to reach the first stage of gain, be that a head amp, SUT, or high gain phono stage. The op amp is designed to drive a 47K ohm input resistance and is thus suitable for MM stages or a low gain MC stage in which the load is 47K ohms. The net weight is only 12.5g, making it somewhat compatible with even high compliance very low output cartridges. I wonder if anyone has experimented with this gadget. I am about to do so myself.