The only difference between the M5500 and black K5510, is their finish. The former boasts a silver bezel and stand, while the latter is black.
The televisions can stream Ultra HD content from Amazon Prime Instant Video, Netflix, and BBC iPlayer, as well as upscale standard definition sources. Both models are also compatible with High Dynamic Range content, to deliver "brighter whites and deeper blacks".
MORE: What is Ultra HD TV and 4K TV? Everything you need to know
On the back of each set, there are four HDMI sockets - two of which feature HDCP 2.2 for use with 4K sources. There are also three USB inputs, and an optical output for connecting to a soundbar.
Both models feature three different sound processing modes that can promote virtual surround, enhanced bass or prevent sound level fluctuations for night time listening.
The M5500 and K5510 are available now, priced at £899 from AO.com.