I used to owna Concentra and bought a pair of mono tube amps later. I went to my dealer to listen to the new Concentra last week, and got to bring it home for a night over the weekend. It's much faster, has better bass grip, and is completely wide open and clean. I'm letting the dealer sell my amps on consignment and I'll be ordering a CII as soon as they go. I'd put the CII over most separates.