I've heard the Hailey in my Dealer's treated showroom paired with a Vitus RS-100, DCS Pucini cd player & DCS Scarlatti dac. The Vitus RS-100 provided the normal Vitus hallmarks of smoothness, tonal richness, mellifluousness & non-fatiguing sound, together with excellent control. The DCS gear was certainly resolving, but I find DCS a bit analytical. Also digital volume controls have limitations. I am sure a Vitus RD-100 & RCD-101 would have had better synergy.
The Haileys are dynamic, coherent, resolving and project an expansive sound stage. The Haileys are definitely smoother sounding than earlier YG speakers thanks to newer (better) tweeters and ongoing refinement of crossovers etc. I wouldn't say as smooth or laid back in presentation as the S5's. Paired with Boulder, Spectral or Rowland, the Haileys would sound too 'metalic' and still a bit bright for my liking.
I've heard the Haileys with Lamm 2.2 mono's, Lamm LL2.1 pre & Ayon front end. In this setup, the Hailey's conveyed the warmth and tube virtues of the Lamms & sweetness of the Ayon, but was under-powered imho. The extreme resolution of these speakers and their tuning means they benefit from from either some tubes in the mix or smooth tube-like ss amps.
The best sound i've heard with YG perhaps unsurprisingly was a pair of Sonja's paired with a Vitus SS-102 amp, CH Precision D1/C1 combo & Gigawatt PC-2 EVO Power Conditioner. The SS-102's great control and wonderfully smooth, rich, effortless sound sounded great with the CH front end. The big Vitus is the only amp which i've heard tame the YG's tendency to brightness. I really enjoyed that listening session.
In summary, the Hailey is a really impressive speaker with exceptional build quality and displays similar class to the Sonja, but imho is best matched with Vitus amps. For sure CH D1/C1 works well also if your pockets are deep enough. Then again, there is the Vitus Masterpiece transport/dac ;) For me personally, I believe your system needs to be balanced. I could have bought a pair of Haileys, but that would have meant making compromises elsewhere which meant I would not have gotten the best of the speakers. Instead I went for the S5's and am building a balanced system around those speakers.