Fantastic news! Even if I do have to wait a bit longer for a pair of Supertrain 121's......
I'm sure a speaker will be fitted. Since that has been the case with the 071 and 201 models. Even the 141 came with a factory fitted speaker cradle.
Yes the 121 was originally fitted with the EMD 8-567CR, same as the 141 locos. The 181's came with the 645E but some 141's were later fitted with 645's taken from the C Class when it was withdrawn. The push-pull 121's were also fitted with 645E's.
Loksound have accurate sounding files for both the 141 and the 181. IIRC, Mr Soundguy's ZIMO decoders use a recording from a 645E so they would be accurate for later 121's.