Is it safe to connect a 4 speakers to a 4 ohm amp?

First, you must know: There is no 4 ohm amplifier. All audio amplifiers have an output impedance of smaller than 0.5 ohms. So you use impedance bridging. No problem to connect the 0.5 ohm output to your 4 ohm loudspeaker. Scroll down to related links and look at "Impedance bridging - Wikipedia".