Buying A New AVR or AV Amp: things to look out for

- at least 7.1 capability with built in amps
- latest sound formats:
DD, DTS are basic, you also want Tru-HD and DTS-MA as a standard as well more 3D formats like DTS-X, Dolby Atmos.
These days, not only the video gets upscaled, but you also have upscaling of sound, using tech from Dolby and DTS: Dolby Surround and DTS- Neural X.

You can never have enough power and do note that what they state on the box seldom gets realised in real life. Look at the power consumption for an idea. Eg, if the power drawn from the wall is 700W, and there are 9 channels, even if the amp has an efficiency of 80%, that means you won't see more than 60W per channel when all channels are operating.

However if you live in a domestic setting like a flat and use a subwoofer, this will be enough if you use typical speakers. More power allows you to use less efficient speakers and will give you more dynamism and headroom for the explosive moments.

HDMI inputs and version.

For 3D, you only need HDMI v1.4 but if you want the full function, get the latest version and currently it's HDMI 2.0b. HDMI 2.1 will come, probably in 2019, but there's scant info right now.

You should get an amp with at least four HDMI inputs.

If you do a lot of listening with stereo or legacy gear, make sure the amp has enough RCA inputs for you.

Auto-calibration:
There are many flavors but choose one that is easy to use, especially if you are a beginner. Denon and Marantz use Audyssey, but each company has their own version. Do note that there are different version of this, the highest being XT 32. It's worthwhile getting an amp with this as it also calibrates the bass from the subwoofer. It's very helpful to have this automatic feature, but it does Not take away from usual a SPL meter and measure the individual channels for the best results.

The difference between an amp and a receiver is that the latter has a tuner.

These days many amps also have Internet radio and other gadgets, but remember if the feature count is long for the same money, it means less money was spent on the power section and making the amp sound good.

The larger companies often change models each year, and it's important to see what's new, sometimes buying the higher end model from last year at a discount is a better bet.

As for the DAC and other components used, don't get into a tangle because of it. The implementation is just as important. If sound really matters, a stereo amp will give you far better sound. As a rule of thumb, an AVR will sound as good as a stereo amp costing about a third the price.
So that $1000 amp will be easily bested by a $500 stereo amp.