Your price range seems to be around £1000 for the amp. And the Yamaha AS1000 and AS200, and the NAD C375 are in that price class. Oddly the Marantz Pearl Lite is only about £700. Based on price, the Marantz PM8003 is slightly higher than the Pearl Lite at about £750, though I did see it as low as £575 at HyperFi.co.uk.
Another quality amp to consider, though only 60w/ch is the Rotel RA-1562 for just a trace under £700. Though less power, I've been lead to believe the Rotel 1500 series amps are well above amps like the Rotel RA-06SE, which has more power and a lower price.
Don't base your decision on power alone. Lots of power is nice, but a little less power much better controlled is to an advantage. Some of the very best amps out there only have a modest amount of power.
Next, can we ask specifically what speaker you have, or what speakers you will be using with this amp?
Next, do we understand right that you are going to try an integrate this amp with an existing AV system?
Given your general description of what and how you listen, I would say you are on the right track. The Marantz, Yamaha, and NAD should all suit you nicely. But, we really need to know specifically what speaker these amps will be driving.
Also, we need a declaration of budget? From what you have said, I would guess we are in the roughly £700 to £1200 range. But can you go as high as £1500. An alternative might be the Marantz PM 15S2.
If you are down on the lower end, you might want to contact XTZ and inquire about shipping on the XTZ A100 D3. All indications are this is an outstanding amp with tons of power, and five digital inputs. Priced at about £625.
Here is the source in the UK -
XTZ Class A-100 D3 Integrated Stereo Amplifier Silver and Black | Integrated Amplifiers | Amplifiers | Audio Sanctum
Here is a link directly to XTZ (Sweden) -
Class A100 D3 Black/Silver - XTZ | Sound in balance
There is currently a discussion going on comparing the XTZ A100 to a Arcam A28 costing nearly twice as much -
XTZ A100-D3 vs. Arcam A28 + rDAC
The testing and the discussion aren't finished yet, so well worth checking back on that discussion periodically.
Again, in this price range, I don't see how you can go wrong with any of the amps. The only thing that can refine the selection more is to hear all the amps on the same speakers, and see if one amp appeals to you more than the others.
Steve/bluewizard