A is pretty good:
Audio Note
Audio Research
Art Audio
Avante Garde
Audio Aero
Abbingdon Music Research
Accuphase
Advent Corporation
Apogee Electronics
Audio Alchemy
Audio Analogue
Audio Partnership
Audio-Technica
Audiolab
Audiopax
Audio Note
Audio Research
Art Audio
Avante Garde
Audio Aero
Abbingdon Music Research
Accuphase
Advent Corporation
Apogee Electronics
Audio Alchemy
Audio Analogue
Audio Partnership
Audio-Technica
Audiolab
Audiopax