I too, use the 'ping' method on old wheels. There is too much stiction in the spoke nipples on an old used wheel to have a spoke torque wrench be accurate. However, when I build a wheel myself, I use anti-seize on the spoke threads. I use the spoke torque wrench. It does do a better job than by ear. To do this on an old wheel, you would need to remove the spokes, chase them with a tap and die, anti-seize. Ugh, I need a nap!