I don't buy the prejudice against mass market Japanese electronics from the 70s and 80s at all.It's generally comparable to equipment sold today, and better than some of the odder stuff at the higher prices.
There is nothing wrong with excellent specs, other than they sometimes aren't necessary for good sound beyond a certain point though it depends in which area you look.
Back in those days cassette and FM were serious sources and the spec was a good indicator of audio quality. Both mediums are pretty flawed, therefore the higher end products were very audibility superior. Different thing for amplifiers - if 40w was enough then a Sansui AU317 with it's 'ok' spec will sound no worse than a model topping the range.
Technics made some absolutely stunning cartridges the like of which simply don't exist today. Technically superb with amazing specs compared to what is common 20-30 years on, so there are cases where pushing the specs was very worthwhile.
Having sung the praises of Sansui and Luxman, that's an anti-Japanese prejudice?
Pioneer made some amps with, for the time, amazing specs. SA9100 for example. Just didn't actually sound very good if you did something inconvenient, like connected it to a pair of 'typical' loudspeakers of the era, say BC1s or Kef 104s. (Much happier with JBLs or Altecs or something else easier to drive. Although I once made the mistake of hooking up a pair of Lowthers and f*** that was a horrible noise...). But certainly the matching tuner was superb and they did make some very fine cassette decks. But to my ears, a lot of the time the same was true of the likes of Akai, Trio and Technics amps, beautifully made, often (there were exceptions) didn't actually sound that good in comparison to European opt.
At the time, I worked for a dealership which held agencies for Sansui, Pioneer, Luxman, Akai and Technics as well as Sansui. On the 'other side' we had Armstrong, Rogers, Cambridge Audio (when they weren't on fire), Sugden and er, Tandberg and HK. Leaving Luxman aside, of the mass-market Japanese options, I'd maintain Sansui maintained a higher level of consistency and quality with regard to a 'house sound' across the range than the others and it would be my preferred choice for a 'one brand' system.
I'm afraid I don't accept the argument the 317 typically sounded no different to say, a 919.