Great sounds from YC using those external effects .. my first organ I got when I was 15 was the YC-25D (ivory color) which I played with my first band together with Yamaha's first synth SY-1 .. years later I found a YC-45D on eBay in almost new condition and I bought it immediately :)
Thew YC-25D is a good one as well and quite rare in ivory! The SY-1 is very cool and in my opinion better than the later released SY-2 (with more features). I had both for a while. Sadly both are gone for years
