5432: clarify op-amp label

In case the x32 notation (somehow) looks like 32 op-amps in series.

5432.tex

@@ -106,6 +106,7 @@ All channels can be updated simultaneously.
         % Connect DAC to Op-amp, label op-amp width x32
         \draw [-latexslim] (dac.west) -- (amp.west);
         \node [label=below:\tiny{Op-amp x32}] at (3.6, -0.2) {};
+        \node [label=below:\tiny{1 per ch.}] at (3.6, -0.45) {};
 
         % Connect Op-amp to EEM OUT and HD68
         \draw [-latexslim] (amp.east) -- (hd68.east);