I haven't directly compared the H20 Signature S250 directly to any of the Mark Levinson amps but have directly compared it to my Audio Research VT-100 MK 2 tubed amp for 3 weeks. I found it to sound better than the VT-100 in a number of ways (see the link below). I have directly compared both the then top-of- the- line Mark Levinson and Krell amps back in 2005 to my VT-100. Neither could hold a candle sonically to my VT-100 in terms of harmonic textures that I value so much to my tubed amp. Incidentally, my preamp is a Great Northern Sound modified Audio Research Reference II preamp used with ProAC D80 speakers, and an Ayre C-5xeMP universal player. Cabling includes Purest Audio, Nordost, Nirvana, and PS Audio power cords with Audience and BPT power conditioners.
No matter how many thread or opinions that you read here or elsewhere, you really need to audition an H20 in your own system to know how well it sounds to you. E-mail Henry Ho, the designer of H20 for a home audition. Thats what I did and never looked back. Just my 2 cents.
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1128648082&openusid&zzRlf&4&5#Rlf