I have a Yamaha A100 (not the 100a as presents in the photo) for quite some years, it is extremely simple amp is turned on, volume left channel, right channel volume ... and Go!
Sound:
This is an amp clean, transparent, very neutral.
I used a lot with Tannoy studio monitors Mini Lynx are neutral and the result is very satisfactory for those seeking natural sounds and doux.Cependant he supports and transmits very many punchy sounds more like house or dance music.
Use:
I plugged in a mixer and various instruments, but the fact is it still must live on a big fat type keyboard Roland or Korg Triton.
With electro-acoustic guitars (Ovation, Taylor) is very pure, very clean.
Finally, do not bother to look Bercy with background music will be a fair bit! The best is still in use with returns home studio neat.