I wasn't overly convinced with R2R DACs when I tried them with the S17 Pro -- nothing wrong with it, just did not wow me enough to spend that much.
What did wow me were Chord DACs; I managed to pick up a Hugo TT for a reasonable price and I have been enjoying it for a bit now. All I can say is, this really did wow me, I'm hearing many veils lifted from my music and it removes that over processed sound I felt I got from my previous DAC on more instrumentally 'intense' tracks I listen to, zero distortion and still maintains that warm signature I love from the amp and headphones.
FPGA DACs are the real deal!