I was considering a Rasperry Pi 4 or 400 model for use with Pianoteq, but I'm not at all clear about whether these SBCs have reasonable sound quality (i.e. ignoring Pianoteq, just the sound capability of the boards).

Any feedback on this ?

I am basically wondering if there is any SBC with decent sound capabilities (doesn't have to be a Pi) as I don't want to have to lug around an audio plug-in as well as a small SBC, as that would make a laptop just as practical.

I don't need production quality audio, but something to the level of what's built in to a PC would be the aim.

Thank you in advance.

The 400 has a bit more processing power (higher clock speed and the heatsink built into the keyboard keeps it nice and cool). However it does not have a headphone jack which could be a major downside. You could plug a DAC into the port on the back.

So if you want the best sound quality with no extra expansion go with the Pi4 for the headphone jack

PS: I would rate sound quality as FAIR (what ever that means) without a DAC

Any feedback on this ?

I am basically wondering if there is any SBC with decent sound capabilities (doesn't have to be a Pi) as I don't want to have to lug around an audio plug-in as well as a small SBC, as that would make a laptop just as practical.

I don't need production quality audio, but something to the level of what's built in to a PC would be the aim.

Thank you in advance.