How good it will work will depend on your Expectations. The Kef LS50 are very clear and present speakers, and should be excellent for home cinema ...but... they have limited bass ... which brings us back to expectations.
I was recently auditioning some Q Acoustic Concept 20 bookshelf speakers, and as part of the audition test, I listened to X-Men with just the Concept 20 - WOW - what a thrilling movie. The speakers were not lacking in quality at all. But, with small bookshelf speakers, you can't expect Rattle the Windows bass. With the right expectation, just those bookshelf speakers could have done a very good job on their own in a TV/Movie system.
The same with the LS50, excellent sounding speakers, as long as you keep it in perspective.
However, with an Active Speaker, there are a couple of things you absolutely need -
1.) Optical Input
- Most modern TVs do not have Analog Audio Out, more commonly is a Optical Digital Audio Out
. So, to mate with that you need an Optical Input.
2.) Remote Control
- Changing the TV Volume will not change the volume on the Digital Out, that volume is fixed, consequently, you need an alternative way to remotely control the Volume of the TV. If the Active LS50 has a remote volume control, you are set, if it does not, you are screwed.
As a generalization, the LS50 is an great sounding Award Winning speaker ... that does what it does, but doesn't do what it doesn't do. As long as your expectation are consistent with the speaker, and as long as the Active Speaker meets the other requirements, you should be set.
The Kef LS50-Wireless does have an Optical Input, so on that front you are good. I don't think it specifically has a Remote Control, but it does have a Control App for your Smart Phone or other Smart Devices. That might give you the remote volume control that you need. The Speaker also has wired and wireless Streaming. The LS50-Wireless also appears to have a Subwoofer Output, so if you want a bit deeper bass, adding a modest Sub should not be a problem.
The Frequency Response rating of the KEF LS50-Wireless is -
Frequency Response (±3dB) Measured at 85dB/1m
* 45Hz – 28kHz (More bass extension)
* 50Hz – 28kHz (Standard)
* 61Hz – 28kHz (Less bass extension)
- Depending on speaker settings
Frequency Range (-6dB) Measured at 85dB/1m
* 40Hz – 47kHz (More bass extension)
* 43Hz – 47kHz (Standard)
* 46Hz – 47kHz (Less bass extension)
- Depending on speaker settings
That means the bass response is high enough that it would fall in the working range of the Subwoofer Crossover, and make integration of the Sub reasonably easy. So, adding a modest Subwoofer would be possible.
A speaker with that rated bass response should have sufficient bass for music, but it is not going to have kick you in the chest
bass that you might get from a full AV Surround system with a Subwoofer.
Which brings us back to your needs and expectations. If you expectations are reasonably within the bounds of what this speaker does, then I would expect you to be very satisfied with the results.
The LS50-Wireless, from the quick check that I did, does appear to have every thing you need to successfully integrate itself into a TV/Movie watching system.