Don’t. Put a resistive divider on the loudspeaker outputs. Dedicated headphone amps are a waste of money if you already have a good amplifier.Connect up a headphone amp?
The currentSolo doesn't for sure, it has two switchable inputs. The Pro-Ject models doas do the Heed, Lehman and Creek models others too no doubt- its more common than notSome headamps do have and input and an output so you can daisychain. My Stax definitely does and I thought the the slee solo did too. My solo is out on loan so I cant check for sure... but if it doesnt maybe you can open it up and sort something out?