Should I worry about low sensitivity (86 at 4 ohm) of Dynaudio Audience 42 speakers? I would be using with Rega Brio 3 (39 watts). What does 4 ohm figure mean? I notice that some speaker sensitivity is rated (i.e. 89 or 90) at 6 or 8 ohms.
The 4-ohm rating indicates that the speaker will require more current than an equivalent speaker of 8-ohm rating. This puts more demands on the amplifier.
The 86db/w/m rating indicates that the Audience 42 is slightly lower sensitivity than average (generally 87-88db).
This means the Audience 42 is not particularly easy to drive.
I have used the Brio3 with the Audience 42 on a number of occasions. It's a good combination provided you don't expect to play at party levels.