To answer your question, yes you need a preamp if you wish to use your external dac. It sounds like an impedance mismatch between the dac and the speakers.
Assuming you want to keep the dac in the loop I’d recommend adding a tube pre like the Freya+ which would give you three preamp sound options along with endless tube rolling potential.
Personally I’d ditch the dac and simplify your system with just the sound node and speakers. You mentioned it sounded much better.
Assuming you want to keep the dac in the loop I’d recommend adding a tube pre like the Freya+ which would give you three preamp sound options along with endless tube rolling potential.
Personally I’d ditch the dac and simplify your system with just the sound node and speakers. You mentioned it sounded much better.