As former owner of a Mephisto and some other Gryphon Amps and also as former owner of Pandora Sonata Sonata Allegro and Electra...
I can say that Gryphon is first class Class A Amp builder they have a home sound its always musical its always powerful any model its not the last word in resolution but if the music touch you who cares i think Mephisto is the best that Gryphon has ever made.
But when we talk about preamps this is another subject another part of the art and i don't thing that gryphon is in premier league they don't take enough attention on volume potmeter to start whit.... Like Dan D'Agostino is also a very good power amp builder but dont get those level by his preamps.
I also owned the Boulder 2010 at gives you a wowww feeling when you hear it first time but later i realized it doesn't have not enough colors and harmonious tonality for my taste.
If some gear is too much wowww from first moment be aware to wait if your opinion is the same some time later.Its always better if the wowwww grows by time
The preamp builders that has understand building a preamp (that i owned or experienced) in my opinion they are building onvery different ways preamps but all very good some even more.... It all depends on poweramp and system matching synergy and your budget.
Robert Koda
Zanden
Kondo (the M7 whit phono a old one is still a very good preamp)
First Sound (the middle level preamps are his best)
MBL 6010
Audio Tekne
Pass Labs XS
Audio Note UK
I dient auditioned Shindo or Ch Precision to comment on it.