My RWS 34 springer airgun in .177 is loud, I usually have to wear hearing protection to shoot it, is the primary source of the noise from the spring piston hitting home or the muzzle?

It's the internals that makes all the noise, the piston being released and coming to a stop. Not much sound comes from the muzzle of a piston gun, not unless the gun is a Co2, pumped, or a PCP.

I'm shocked your 34 is that loud. Perhaps you're having dieseling issues from excessive/incorrect lube.

Yeh something aint right if you need hearing protection to shoot a springer.

It has always been loud, my RWS 52 was the same, had to wear hearing protection.

I'm lost unless you just have very sensitive hearing. How would you say your 48 and52 compared noise wise to a standard 22LR rifle? I've a 48 and a couple 350's( which are truly magnum springers) and never had any issue with noise.