Started collecting pieces for my museum about 7 years ago.
The pieces must have had some technological impact or caused a change in direction of audio to qualify. (this is of course opinon). So far:
A restored Edison cylinder player, A restored "flat disc" player, a Scott FM tuner, a couple early Marantz receivers (gyro-tunes!), Pioneer RT-909 reel to reel, Phase Linear 700b amp & C-4000 preamp, AR turntable, Dalquist DQ-10's,
Technics Linear tracking tableand my pride and joy, a 1957
Grundig "Majestik" console with turntable, reel to reel,
incredible tuner, a rotory knob 5 band E.Q., 3 push button E.Q. settings (the first DSP!), and electrostatic tweeter panels! Koss Pro 4AAA headphones too. In time I hope to add a pristine high end grammaphone (sp?), black widow tone arm, G.A.S. Ampzilla, AudioPulse time delay, Neumann mic,
Garrard Zero 100, Harmon Kardon 4000 casstte,and a few other pieces that will hopefully pass my way. Best of luck to you in your efforts!