Just a thought... what about substitung the two 2SC5551 in the backend stage of the LZ1AQ preamp with a couple of BFU590 ?
The BFU590 seems to have a greater driving capability of the 2SC5551. After all, it is used as final stage for up to 500 mW low power amplifiers...
73? Alberto? I2PHD
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Alberto I2PHD