@papafrgog & @vthokie83-
While I totally agree with your assessments, regarding rolling amp valves; I'll bet the OP could save a passel of $$ (not to mention: possible sensitivity/efficiency matching headaches), were he to roll some warmer ones into his LTA preamp.
Especially: if he's satisfied with the SPLs and performance of his existing amp and speaker combo, aside from that longing for a cozier presentation.
Happy listening!