I also find some older recordings to be light on the bass output. Especially true on some older LP's. I find that simply raising the frequency of the low pass filter and turning up the gain on my sub captures what's missing.
What's up with lousy bass on classic rock recordings?
Few examples: ACDC Back In Black, Van Halen 1, Boston (1), WHO's Next, Def Leopard Pyromania.
The low end is almost non-existent. Digital and vinyl.
It's not my system, I listen to a lot of jazz, other classics like Janis Ian Breaking Silence - bass is rich, full, has slam when appropriate.
Compression? Or were the low frequencies never there? Pretty disappointing.