Here is another slightly grainy photo of the 2150 mono's. It looks like the 2150 has picked up design queues from the 3100 series including the new damped circuit board mounts & what appears to be a new version of the 99H gain stage. Boulder always stamp the model designation on the top of the their gain stages, so I zoomed your photo above Wizard & can make out what appears to be the engraved designation "99H2", thought i'm not 100% sure. Perhaps someone with better photo software can give it a try? The 2150's should give some insight into the design philosophy of the 2110