Good grief, Amanda Lear! As far as I can recall, she only issued one LP...a big disco favourite...and the story was she was an M-to-F transsexual. Whether it was just marketing (this was the era of genderbending rock stars and glam rock after all), I don't know. That odd voice certainly would suggest she was....
the big groups back when I was a teenager in Germany were (in no particular order):
The Three Degrees ("Wwhen Will I See You Again?")
Barry White (okay, not technically "a group")
Anything coming out of The Glorious Sound of Philadelphia -- sort of a take-off on Motown, or a challenge to Motown actually, all R&B/Soul. Motown ultimately won out....
Talking about Heino (odd character) made me think of James Last and the dance albums he cranked out. Sort of an upbeat German version of Lawrence Welk and very popular stuff at Schutzenfests and Oktoberfests. Nice change from yer basic oompa-pa-pa.
On the heavier front --
+ Black Sabbath ("Paranoid" was big)
+ Jethro Tull ("Aqualung")
+ Iron Butterfly (their only good piece was "In-A-Gadda-Da-Vida" -- 27 minutes of it!!)
+ Yes
+ Genesis
+ The Who (of course! "Pinball Wizard" was really big)
+ Jimi Hendrix ("Are You Experienced?", "All Along The Watchtower", "Purple Haze" etc).
+ Mott The Hoople
+ Creedence Clearwater Revival (Okay, so they weren't "heavy" but damn good....I still love "Proud Mary")
+ Cream (before Eric Clapton became a whiney old bugger)
+ Emerson, Lake and Palmer (brilliant!!!)
+ King Crimson (not as well known but equally as brilliant, perhaps even more so. Some overlap with EL&P. Their "In The Court of the Crimson King" was spectacular).
+ T-Rex ("Electric Warrior" was probably the best LP. The rest were a tad too commercial).