New ADCOM amplifier and preamp reviews

Yes, the new Adcom pair would be an upgrade over the Yamaha! 

Great choice on the speakers! Have the earlier generation model (silver 8) and can tell you they are easy to drive, are very clear and can play LOUD.

They don't seem very picky about the front end but obviously the cleaner the better for the best sound.

Might consider a new integrated. Lots of good ones at the $3k point. NAD, Yamaha, Technics, Marantz, Music Hall, Rega, Leak, Cambridge, Arcam...

MA Silver 300's sound great with the Yamaha but I'm wondering if a separated amplifier and preamp will take the sound up a notch or more.

What model is your Yamaha integrated and how old is it? Without that info I don't think we can give you any worthy advise.

https://www.usaudiomart.com/details/649991473-musical-fidelity-m6si/

Thanks all for your suggestions.  Got the Yamaha integrated A-S701 new maybe a year ago at a significant discount.  It sounds great to me but wondered if a $3k amp upgrade would sound better.  I'm happy with the Yamaha though,  BTW, its DAC sounds slightly more detailed than just using the analog outs from the CD and DVD players I use.