To your question is anybody using the Yggy with top notch speakers, yes. I have a friend using the Yggy with Evolution Acoustics MM3, fed by latest Spectral electronics and Sonore Rendu Signature. He compared to a number of dacs in the $5-10k(the usual suspects) with a few home demoed before deciding on the Yggy. Performance further enhanced by a few basic & reversible commonly done damping/isolation mods done by a local tech (details searchable online).
An interesting point is that another friend bought an Yggy to replace his Phazure dac in a much more modest system using Golden Triton Ones and he is thrilled with Yggy too and can hear distinct improvement over the pricier Phazure. Cheers,