Both McIntosh and Lexicon are quite musical power amp that have taste..... together with B&W (England speakers with taste), it reproduce a "mixed" sound. But for the new B&W 800 series, it may be different.
In fact, McIntosh and Lexicon are suitable for the speakers which produce clear and brighter sound (e.g. Focal).
FYI, I am using McIntosh MC2300 and MC302 as 2 channel and Marantz AV7005 + Lexicon RX-7 for AV