Thought my wl4 was just missing a little focus, for want of a better word. Battery was reading 8.8 volts which I assumed should be fine, but since I had the back plate screws off I replaced it anyway. New battery read 9,57 volts. Anyway, might be my imagination but the magic returned. Supposing it wasn't all in my head (and it could be), does anyone know how low a battery can go before it makes a noticeable difference to the preamp.

