I'm guessing 363 is a typo and you've really got a 636. If so then you've invested somewhere around £450 in a receiver, and now plan to take the budget to a grand or more with the speakers. That's a pretty tidy wedge of cash in total. So you really need to know that if you go through with your plan to put the speakers in the corners then you'll be wasting an awful lot of the potential of the system.
Corners are bad places for most speakers. There are two main problems. One is that that sound bounces off the walls (and ceiling if mounted high) as well as coming directly to you from the speaker. That's like having three (or four) speakers placed closely together but all slightly out of time with each other. The result is that each proper speaker sounds vague and unfocussed because of the secondary reflected echoes. It's not as bad as the indistinct sound of announcements in say a railway station, but it's certainly not the effect you want in any sort of domestic audio system.
The second problem is space. With the speakers so far apart there's a gap or hole in the sound stage so you hear three distinct (but unfocussed) sources. It spoils the effect that should make you forget you're listening to speakers at all. There are speakers that are happy being mounted directly on a wall. But putting them in the corners of the room isn't where they're designed to go for all the reasons above.
A rough rule of thumb for speaker positions is the equilateral triangle. That's one where the length of each side is the same. If you imagine your seating position at one corner of the triangle, and the front -left and -right speakers at the two other corners, then the distance those speakers are apart is the same as the distance to each from where you sit. Once you have a roughed out position for the front L & R, then the centre speaker goes at the mid point between them. For good measure, the front three should all be at ear height but that's not always practical. The speakers can always be angled up or down to point at your listening position.
The surround speakers are often referred to as "rears" but that gives the wrong impression of where they should be placed. They don't go behind you but to the sides. They should be mounted on the side walls, about parallel or slightly back from parallel to the main listening position. Height-wise, these should be about 5ft (1.5m) from floor level. They'll be above head height when you are sitting down.
Okay, so that's dealt with speaker position and whether they can go on wall or not. Now lets deal with speaker choices.
The first thing everyone will suggest if you have the opportunity is to buy a sub from BK Electronics. The reason is simple. Pound for Pound they perform better than equivalent products from the major speaker manufacturers. They're all correct as well.... except when buying a better sub means taking some large compromises on the speakers in other areas. My guess is that for you, speaker positions away from the back walls is going to be an issue. You'd be better off with speakers that are suited to wall mounting. This is primarily for aesthetic reasons (position and physical speaker size), but now you're learning more about acoustics then you'd like your investment to sound good too. After all, it is a '
sound system', so shouldn't the sonic qualities be a priority.
Let's say for a moment that you ignore my advice and go for the entry-level BK sub. What would it be and what would the partnering speakers and accessories come to?...
BK Gemini II - £215 (inc signal cables) + delivery (£26) = £241
Remaining balance £259~£359 to buy centre, fronts, surrounds and speaker cable + brackets or stands.
Possible combos:
Tannoy Mercury VCi (centre) £105 + 2x pairs Tannoy Mercury V1 (2x £70/pr) - sub total £245 + cables (£60-£70) + wall brackets (£30) - Total £350
Mission MXC1 (centre) £100 + 2x pairs Mission MX1 (2x £90/pr) - sub total £280 + cables (£60-£70) + wall brackets (£30) - Total £385
Tannoy Revolution DC4 LCR (centre) £100 + 2x pairs Tannoy Revolution DC4 (2x £150/pr) - sub total £245 + cables (£60-£70) + wall brackets (£30) - Total £500
These aren't the only choices; there are products from Monitor Audio, Q Acoustics, Dali, Jamo, Wharfedale to name but a few. But I've already hit what I'd consider to be the main choices that come in to your budget range.
Now let's have a look at what I'd consider to be a perfect choice for you... It's the
Monitor Audio MASS 5.1 system at £599 including the matching Monitor Audio sub. Monitor Audio has been (IMO) one of the leading speaker manufaturers making compact satellite speakers that still perform well for music as well as for movies. That takes some doing. It started with the Radius system that became the go-to product range for this sort of thing. However, that's an expensive solution for 5.1 at £1500 now. For some time MA have been looking for a way to emulate the success of Radius range but at a more accessible price. A couple of years ago they brought out the Vector series, but the styling was a bit challenging for many. The replacement is the MASS system, and I think they got it right. The satellites and centre are small enough to be discrete (224 x 128 x 128 mm) yet large enough to house some decent sized drivers that deliver for music. They look very smart too. The sub is good enough to shake your room when dinosaurs stomp about, but agile enough to follow the complex bass rhythms in music. You will need to buy speaker cable and wall brackets. The MA wall brackets are £15 each, but B-Tech makes the BT33 which are just £12 per pair and they'll easily hold the weight and (IMO) they're a better design too.
