Depending on your taste, Rega has a decidedly warm sound profile for their amplifiers. They also tend to do best with speakers that are easy to driver in terms of impedance. They may be rated for 4 ohms but they will not be at their best.
I would look at a neutral to slightly forward sounding speaker with a min impedance above 4 ohms, ideally above 6 ohms. What you haven't mentioned is if they should be stand-mount or floor-standing.
My initial thought is that Paradigm would be a good option but it would come down to the specific model. This would lead to a pretty neutral sound profile. Another option would be the Monitor Audio Silver line (200s) and paired with the Rega, would be to the warm side of neutral.
I would look at a neutral to slightly forward sounding speaker with a min impedance above 4 ohms, ideally above 6 ohms. What you haven't mentioned is if they should be stand-mount or floor-standing.
My initial thought is that Paradigm would be a good option but it would come down to the specific model. This would lead to a pretty neutral sound profile. Another option would be the Monitor Audio Silver line (200s) and paired with the Rega, would be to the warm side of neutral.