I drove my U-3’s (updated toroids and PX panels) with Wolcott mono blocks for years. They worked very well. Plenty of punch, great highs, open mids, wide and deep soundstage. Last year I replaced them with the PS Audio M1200 Class D monoblocks. The M1200’s were better in every category. The timbral accuracy of all instruments, attack/sustain/decay ,micro dynamics, and ambience retrieval were immediately noticeable improvements right out of the box. After 200+ hours, they still were getting better. Darren Meyers knows what he’s doing to make those ICE modules sing.