hamdib wrote:

I own Pro-ject Juke Box Turntable system (amplifier is fitted inside)
Amplifier specifications:Bi-Phase PWM circuit 2x30W@4ohms/2x20W@8ohms

Looking for matching speakers

My choices are
Focal bird
Q Acoustics 2010i
Boston Acoustics A23
Boston Acoustics A25
KEF C1
KEF C3
Dali Zensor 1
Monitor Audio BX1

Because your amplifier is very low-powered, the first requirement is very high sensitivity speakers. The C3 is 88db/watt, which is as low as I would go. Anything lower will limit your maximum volume and dynamics very severely! The Dali and BX1 are also 88, which is the low limit for you.

You would be far better off if you could find speakers that have a 91 db/watt sensitivity or higher, which will allow more volume without distortion.

The Klipsch R15M has an exceptionally high sensitivity of 94 db/watt, which would be my recommendation for such a limited amount of amplifier power. The sound quality may not quite be as good as the Dali, but on the other hand the Dali may not put out enough sound.

With most of the speakers on your list you might be very disappointed in the amount of sound you can get before distortion sets in.