With £2000 to spend, I would recommend about £500 to £800 for the amp, and perhaps, £1200 to £1500 for a pair of speakers, though you must consider the possibility of some additional expenses in the form of wires and interconnect cables.
The broad and general guideline is speaker at about twice the cost of the amp. Though it varies from person to person, below is the formula I use -
1x to 1.5x = Turntable
1x = CD Player
1x = Amp
2x = Speakers
Of course this just gives you an initial framework, you are free to deviate from this as you please.
Next we need to consider the full range of use for this system. Is this a pure music only system, or will it be combined with your TV for movies?
If combined with TV watching, then we might want to consider either a DAC or an Amp with Digital Inputs. The real point here is Features, what specifically do you need in an amp? A blend of power and quality? Absolute highest quality which implies basic power? Or higher power and basic quality? Though in this price range any amp is going to sound good. Also, features like Tone Controls, some amps have them, some don't, what is your preference.
For example, you can get the highly regarded 120w/ch Rotel for about the price of a 50w/ch NAIM. The NAIM being a stunning quality amp, but just basic power.
I'm only vaguely familiar with Apple TV, but if that gives you Music Streaming capability then fine. But this is another area where you might want to step back and re-evaluate your needs. There are other streamers specifically for music. Again, not being familiar with Apple TV, it might already do the job just fine.
Sorry, to say I've not been a big fan of Cyrus, but that is more a personal style preference rather than an indication of anything wrong with the amps.
A Rotel RA-1520 with 60w/ch (£695) is worth considering. If you can push your budget, the Rotel RC-1550 (£495) Pre-amp combined with the Rotel RB-1552 125/ch Power amp (£695).
Again, pushing your budget, but the Arcam FMJ-A28 with 75w/ch (£999) is worth considering.
The suggested Cyrus 8A is a pretty steep £1200 with 70w/ch. There are a couple of versions of this amp with DACs built-in.
Again, think about the features you want from an amp?
For speakers, while the Monitor Audio RX8 (£1049/pr) and the Bowers Wilkins 683 (£999/pr) are fine speakers, they are slightly beneath your suggested amp.
At this stage we would need some sense of how the speakers are going to be used, and the types of music you listen to. Also, the general volumes you listen at.
Good speaker are the Dali IKON 6 floorstanding at about £1099/pr. The Larger Dali IKON 7 are about £1599/pr.
Depending on your need for bass, the Focal 836V are stunningly clear speakers, and well worth the £1679/pr price tag. These are not a bass heavy speaker though the response is good, and stunningly clear. If your bass needs are more modest, then the Focal 826V are £1349/pr. (focal.com for specs)
Right now AudioAffair.co.uk has a sale on the better Focal 836VW for an extremely modest £1599/pr. These are well worth checking out. They use the "W" type drivers from the better Electra line of speakers rather than the standard "V" type drivers from the Chorus line.
Depending on your preference for style and sound, the Acoustic Energy Radiance 3 for £1095/pr are worth checking out.
As to the ratio of amp price to speaker price, I've simply provided a guideline. If you prefer to sink more into the amp and less into the speaker, more power to you.
My personal preference would be for Rotel and Focal. But that takes you over budget (£495 Pre +£695 Pwr +£1599 Spkr = £2343) but I would expect that to be a stunning high powered system. Though again, that reflects my preferences for features.
Again, the features you want and need are important. As an example, if TV/Movies is involved, the Harman Kardon HK990 is a massively powerful amp crammed with features like Room Eq, Electronic Subwoofer Management, Buit-in DAC, twin Subwoofer output, Phono Stage, 150w/ch, and those who have this amp have nothing but Praise for it.
If you want minimal features and absolute top quality, then the Naim Nair 5I/2 with 50w/ch at £875 is hard to beat.
Many people like the Cyrus amps, but in terms of style and power, they don't appeal to me personally. I also think the Cyrus 8a is out of proportion to your speakers. Though again, there is no right or wrong, it is a matter of personal choice. The Cyrus 6a with 50w/ch priced at £699 is probably more in proportion to your budget, but a bit lean on power. Though high quality amps like this tend to drive a lot stronger than their rated power would imply.
For me, and this is just me, the Rotel Pre/Power + Focal 836VW would certainly be worth checking out. The Focal 836VW are currently discounted by about £800. I've heard the 836V and was mightily impressed, and would expect the 836VW to noticeably outperform what I heard.
Just a few thoughts.
Steve/bluewizard