An old duffer who turned 90 or finally hit 90? More likely the latter I think. :-)
I do believe you could improve your systems sonics with a different pre-amp.
I use the PL3 with a PL5 and combined they are excellent lacking only a little bit of ultimate resolution and deep bass power. BUT, seperately, the PL5 is deficient in the bass when driven by other pre-amps I've tried, and the PL3 is somewhat dark and closed in with the other amps I've matched it to, including tube amps with a high input impedence (I assume yours is 100K, not 100, and a technical impedence match would not be a problem).
Now what pre-amp and how much money you might want to chase after it is another thing, but you should try some out. You might try out one of CJ's pre-amps that compliment your amp.
Hope that helps a bit.