I have a few things:
A Powerbook G3 Lombard with OS9 and Reaktor 4 and Ableton Live 3. You have to bounce a lot but it can make tracks. The GUI isn’t very responsive. I wish I could find my Reaktor 3 dongle to convert the Weedwacker ensemble to Reaktor 4, but it’s gone. That was my first favourite synth. I bought Reaktor 3 and a (long-since failed) iBook G3 when I turned 18 and got all the money my parents had been saving up for me since I was born… literally spent it all the day after my birthday, haha. I wish I’d explored Reaktor more, coming back now with 15+ more years of synth experience it actually seems pretty great. The Lombard is the last one with SCSI, it sits nicely on top of an old sampler like an E-mu Ultra.
Then there’s the G4 tower with 3 Pulsar cards. This isn’t set up right now. The tower is a hand-me-down from my brother who bought it new when it qualified as a super computer, and I’ve used it for various things over the years… I bought the cards a few years ago because it seemed really cool, but after a bit I found out I actually didn’t like the sound at all. Should get a MotU 424 card for it maybe.
Earlier this year I got a Quadra 650 with a Digidesign SampleCell II card and a ProTools Nubus system. Unfortunately I can’t get the ProTools system to quite work, I think the interface (Avid branded 888) is faulty. The SampleCell is pretty fun, though, when paired with Turbosynth it’s endless fun. And I love the black and white System 7 interface. If anyone has an old 20 bit 882 or 888 interface they don’t need, I can give it a good home.
I have to say though, all in all, I think of this as separate and a hobby. These were great instruments/tools when they came out and they do exactly what they did then today, but a five year old laptop and some free software is much better if you want to actually make music. Mac OS before OS X crashed a lot and screen redraws were very slow, and you absolutely will lose work and hate yourself… but me, I grew up on it. That OS 9 boot screen is just magic to me.