Good partner amp for Egglestonworks Anda II

Hello everyone, I was lucky enough to get a used pair of Eggleston Andra IIs for a good price, so far I'm loving it but I'm getting people telling me that the Andras are hard to drive and that i should upgrade my amp.

Although I'm quite happy with the Andras on the Mcintosh 275, I recently heard my previous speakers the Dynaudio c1 hooked up to kilowatt monoblocks from Bryston and I was amazed at the difference in drive and dynamics the Brystons made.

Now it's got me thinking if I'm maximizing those four 12 in woofers, obviously not right? I was hoping some of the more experienced forum members or other Andra owners can give me some advise on a power amp that's well suited to the Andras, I'm also willing to consider an integrated amp and I was also wondering if I should consider passive bi-amping since the Andras are bi-wireable. Thanks in advance.