I agree with several other folks who say your sound will be very different switching out from the McIntosh. You need to hear the Bolder or other recommendations before making a switch that big. I am a former Mcintosh owner and in my case moving to another brand gave me a big improvement over the sound of the Mc. But to be clear, nothing wrong with McIntosh, it just has it's own voice. And I realized I liked other amp's sound better. You may not find that to be true.
Integrated Amp upgrade path
I’m currently using a Macintosh MC 8900 to drive Vandersteen Treo CT’s, with a six pack of Rel S510’s, streaming only. I understand Boulder will shortly have a software upgrade for the 866 that will include an Air Play equivalent to allow full use of most streaming services. Looking for thoughts from anyone with experience with the 866: how much of an an SQ improvement with this upgrade? Incremental? Immediately noticeable? Thanks for any help!