In the price range you’re looking at for speakers, one usually invests in beefier amplification. Keeping the YBA and swapping the speakers is going to severely limit your speaker options. That isn’t to say you can’t find a match that suits your tastes, but if you’re spending $3k+ on speakers I’d typically expect complementary amplification that can deliver at least 150w - 200w.
I’m still of the opinion that adding tubes to the signal chain may satisfy your requirements. To be honest, I don’t think you’re looking for neutral sound. You want exactly what tubes deliver, large images and a warm/full presentation. Kenrad VT231/6SN7's will deliver exactly what you're looking for.
https://forum.audiogon.com/discussions/black-glass-kenrad-6sn7s-take-the-cake
Edit: Not sure where you live but I think it’s worth your while to hit up the local hifi shops and take your DAC with you. It might help you identify what components in your current setup aren’t fitting your desired sound profile.
I’m still of the opinion that adding tubes to the signal chain may satisfy your requirements. To be honest, I don’t think you’re looking for neutral sound. You want exactly what tubes deliver, large images and a warm/full presentation. Kenrad VT231/6SN7's will deliver exactly what you're looking for.
https://forum.audiogon.com/discussions/black-glass-kenrad-6sn7s-take-the-cake
Edit: Not sure where you live but I think it’s worth your while to hit up the local hifi shops and take your DAC with you. It might help you identify what components in your current setup aren’t fitting your desired sound profile.