I just came across this topic about the Yamaha A-1. I inherited a black one, bought by my dad around 1980 or so. It's in my basement now for some 15 years. I don't know if it's in good working condition. Will try soon. Price was about 1700 Dutch guilders (about 800 euro) which was a lot those days, especially for an integrated amp with only a modest power output even for those days. It had a relaxed, laid back sound. Note that the unit came with some plugs to match impedance of MM cartridges, which is quite rare I think. The MM phone amp is oké but the MC amp is noisy.
I also got from him legendary Yamaha T-2 tuner, one of the best tuners ever made. Looks nice on top. Quite different as the mainstream those days.
BTW, there are two massive transformers in the A-1, not one per channel but put in parallel to "cancel leakage flux " or something as stated in the manual (?). Also, there is no real pre-out with this amp. That "pre-out" comes directly from the main amp. That's why there is no separate input for the power amp I guess.
Another interesting detail: there is no separate balance control. The big volume control consists of two concentric knobs (so in fact dual mono). With a dual mono ALPS potmeter behind it.
Unfortunately the door with the controls behind is broken off but I still have it somewhere.
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