I'm a big fan of integrated amps. I've owned quite a few of them, both solid state and tubes. This is one integrated I actually found myself going back to.
Back about 2 years ago I picked up an 840A on the used market sort of as an interim solution while my system was in flux and I was trying to decide which direction to go next. I was actually very surprised by this amp!
I really shouldn't have been surprised, mind you. I am a big fan of Cambridge Audio gear. I think they represent some of the best bang-for-the-buck gear in the mid-fi market. Besides the 840A, I've also owned the 540R HT receiver, the 640C CDP, the 650C CDP, and the DAC Magic. All pretty darned good.
What did I like about this amp? Well, the first thing I noticed was the build quality. This thing is built like the proverbial tank. It is heavy and solid, and put together with quality parts. The pre-amp and power amp sections are discreet units within the chassis, almost like having two separate pieces of gear stuff within the same box. The torroid transformer for the power amp section is oversize and seems to be of excellent quality (as is everything CA).
Let's talk about the volume control briefly, since this comes up in forums a lot. People either love or hate the volume pot on this amp. The clicking drives some people crazy. As you adjust the volume, the relays within the volume control emit a quite audible click for each graduated step. It is non-defeatable. Love it or hate it, you can actually feel the quality of the control as you turn it. I happen to love it. The volume control on this amp is actually one of the best I have ever seen. I would have to guess its accuracy between the left and right channel would be within a fraction of decibel, making for a perfectly balanced stereo image.
Let's get to the most important thing: The sound. This is a very smooth, muscular amp. If you like to head-bang (or even just like to rock out with loud music), this is the amp for you. Tons of headroom and power, and precise, BUT without being bright. People often describe the CA house sound as being lean or neutral, but I would have to disagree. This is actually a rather warm sounding piece of gear.
As an aside, I own a rather ancient Bryston 2B amplifier, that was sent back to Bryston to be professionally refurbished and tuned up. When I got the amp back I put it toe to toe with the 840A (using the 840A as a pre-amp for the 2B). The power amp section of the 840A absolutely smashed the 2B. There was no comparison.
As far as connectivity goes, this amp will have everything you could possibly need. Lots of single-ended inputs, an XLR balanced input, pre-amp outputs, gain trim for each input channel, and even the ability to assign an fixed input channel so you can use this as a power amp, or with your HT.
Going back to how much of an impression this amp made on me back 2 years ago - when I heard recently that this amp was discontinued, and the MSRP had dropped from 2k to 999.99, I jumped on that deal and bought one. It's a keeper.