be aware, this will be a long post. be sure to read through and not just skim it as i do not want to repeat myself.
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there is no reason to appologize per se, but giving us more information and being more clear would certainly have caused less confusion than we had above.
- how many channels (2.0, 2.1, 4.0, 4.1, 5.1, etc)
- what you want to connect up as sources (pc only or if you needed aux inputs)
- what kind of speakers you wanted (powered which work alone or unpowered which need an amp)
- in relation to above bullet, a pc system or home audio system
- what size of speaker you can handle in your space (though for your budget anything bigger than bookshelves is not going to happen)
you have already answered some of the above, though some points also i had to guess on or perhaps you arent sure about yet.
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1. honestly in your budget you will NOT be able to afford a "quality" 5.1 home theater system. you might be able to find a very cheap "home theater in a box" aka HTIB system but many models only offer 5.1 input via the dvd player included. external input may be only 2.0 and faked into 5.1 with dolby pro logic. it depends on the system, but most cheaper ones at least are limited. so-called true surround systems (based around a receiver) do not have connectivity problems like this. likewise, pc 5.1 systems will hook up to computers fine.
2. depends on your future plans and type of speakers honestly. 2.0 stereo receivers are cheaper than 5.1 variants normally but are more limited. often they (2.0 models) do not have a LFE (subwoofer) channel on many models which makes subwoofer hookup a bit more complex. all of the 5.1 variants have an LFE jack and will allow you to connect more speakers up in the future if you ever went larger. if you are going for a small simple system as i stated before going with a small amplifier is also an option instead of a receiver. for smaller bookshelves this should be fine.
i have had good luck with the dayton dta-120 as far as small amps are concerned. it really is much nicer than those cheap lepai units you can find around. for receivers, sony and onkyo make decent low priced models. yamaha and pioneer also are decent brands but often are much higher in price for even base models than the previous two.
3. not everyone can A/B compare every set of speakers, nor can you expect them to. also, as to what sounds best it really depends on your own preference and ears as what i like you may hate and vise versa. as i stated previously in general i have liked klipsch's sound signature and i personally own a set. i did A/B/C compare some satellites (bought), bookshelves and floorstanders from them in a theater room and liked how they all sounded but klipsch bookshelves were out of my budget at the time ($1300 was enough to spend for me on my setup.... bookshelves would have been much more). i have not heard wharfdales personally but from what i've read and have heard back from feedback they are at least reasonably good for the 9 and 10 series. i can not be sure about the newer models. i know the mackie cr3/cr4 are good and i've heard them in person but not the model you are talking about. likewise, jbl does make some decent speakers but i dont know that model. do realize there are many models out there and listening to each and every one is certainly not possible for most of us.
the best i can say is:
- i generally like klipsch products
- i've generally heard good things about wharfdale (9 and 10 series)
- i liked the mackie cr3/cr4
- the audioengine a2 was okay, but the mackies above were cheaper and sounded better (to me, opinion)
- i've heard some jbl speakers and some models sounded good
- the micca pb42x (mb42x is unpowered ver) sounded okay to me
as far as prices are concerned, you need to look at products within your budget. there are speakers which cost over $4000 each from klipsch for example while there are also products under $200 for a pair. will one sound better than the other? i would hope so! also do recall to budget for an amplifier of some sort if you are going for passive speakers.
as an example, klipsch has a set of two for $200, the kb-15 icon which is respectable. sure, its only considered entry level in the big picture (and honestly your budget really is only for "entry level" when talking about home theater) but that does not mean entry level is a bad thing nor do such products sound bad.
4. generally monitors lean towards neutral signatures while hifi can have any signature. monitors tend towards being self-powered but that is not always true. mostly i consider monitors, hifi and home theater products interchangeable in most cases and the terms themselves as more marketing terminology than anything else. for instance a product like the mackie cr3 could be used as a studio monitor while at the same time used as a small hifi system. if you want to get technical there are things like high-fi(delity) mid-fi and low-fi but generally advertising lumps all half decent speaker systems into hifi which is really a misnomer. the products you're actually going to end up buying for your budget are low-fi or mid-fi products in the big scheme of things though in todays world they are called hi-fi. confusing? i know, but this is why i said to not focus on names so much. what is important instead are its features, signature and build quality. at best you can use its tag of hifi, etc to signify what kind of target audience they are meant for. home theater products are generally meant for home theater systems for example and might not be a neutral sounding system but you could certainly use a pair for pc general use or even for mixing/monitoring. some monitoring headphones for example are fairly bass heavy. it all boils down to preference.. and preference alone.
5. you are talking about sound frequency.
here is a good example describing these
http://cloud.addictivetips.com/wp-content/uploads/2014/12/Instrument-Sound-EQ-Chart.jpg
as you can see, bass (or lows) are on the left, midrange (mids) are in the center and treble (highs) are on the right. be aware than various sounds may occur across a range of frequencies (as seen in chart) but might peak in greater volume on some frequencies.
for example, female vocals rely heavily on good sounding treble/mid extension but still may have some bass tones. drums might sound better one equipment capable of good mids but bass extension gives them more kick and treble extension gives them a bit more snap.
as far as treble energy is concerned, generally it can be described in three ways
how articulate or detailed treble is. more detailed speakers will show greater resolution or be able to play the smallest little details accurately. while this can sound great to some, it could make poor quality audio sources sound bad as well. sometimes too much detail is fatiguing for your ears while sometimes too less sounds horrible, lowfi and dull. its all about preference.
how powerful a response the speakers give for treble. this is relating to a speakers overall frequency response curve or general sound signature. for example a model which had "excessive" treble in relation to other frequencies might sound tinny and might lack some low end power or bass behind it to give the sound a more full sound to it. a lack of treble can make audio sound less crisp and dark.
how far they extend up into treble frequencies. you can have both a powerful response and detailed treble without them extending far into the spectrum, the three are really not tied together completely. in any case, how far they extend means how far up the treble scale they will play. too high a frequency paired with high detail might make them a bit piercing or sibilant (think of sibilance as the harsh S sound on words like HISS when someone has a lisp). of course whether or not a speaker is sibilant depends on the audio source (file) not just the speaker.
what does all that mean? its all a general understanding of what treble is and how it can be described on speakers. hopefully it can at least give you an idea how a speaker might sound to you given what people describe it as.
from what i've heard, dome tweeters can tend to be less bright (or powerful on the treble end) as horn tweeters. heres a link where someone is describing it
http://www.avsforum.com/forum/91-audio-theory-setup-chat/1398576-horn-vs-dome-tweeter-design.html
klipsch tends to use horn tweeters and although they are supposed to be brighter, i've been nothing but happy with my setup. sure, the speakers are capable of nice bright and beautiful sounding treble but i've never heard them go sibilant nor be too piercing as they were balanced (opinion) to my ears. my ears and preferences might be different from yours though. i will say that i do not care for piercing treble or sibilance at all though and that i personally find such things very irritating but i have not experienced that yet with these speakers (though be aware... if you play a source which is recorded purposefully to be sibilant or bright on treble you could experience it.. i'm talking more about general sound, movies, games, music perspective)
this is also not to say that dome or more mellow sounding speakers are bad.. it really REALLY depends on your own preferences and what you like to listen to.
6. channels. 2.x references that its a two speaker setup. x.1 references that its a one subwoofer setup. 2.0 is two speakers only, 2.1 is two speakers plus subwoofer, 5.1 is five speakers (generally front l/r, rear l/r and center) plus one subwoofer.
if you want to be technical, you "can" upgrade to a 5.1 from 2.0 powered speakers in a way, but its generally not done like that. normally most 5.1 sets have a larger more powerful center channel for things like vocals. you could use three 2.0 cr4 sets for example to make a neat little self powered 5.1 setup (one set of two would be used for the center in this case.. why not just 1 for center? because you buy the sets in pairs.. why would you put a speaker on the storage shelf and not use it?). if you had individually purchased self powered speakers you could just get 5 speakers. sure, the center channel is just a normal speaker but it could work.
normally people who go 5.1 get receivers and go with passive speakers. active speakers are generally used more for 2.0 sets. its not that you cant do it, just that its less common.
7. some of the others here know a few good brands but what is available for serbia is beyond what we are likely familiar with. prices can also vary heavily and you can not expect us to do all the footwork (which can take hours) to track down what a particular product cost IN YOUR COUNTRY. using euro sites and us pricing is a good start, but when searching for products in country you may find the price varies quite a bit and the availability or variety of products might be less.
there are of course other audio sites and home theater forums but many are either USA based or europe based. finding good information on countries is very hit or miss.
honestly the best for you would be to either link products or brands available in your country for your budget and ask if they are good or not.
8. depends on what kind of cable. self powered sets generally take either 3.5mm or rca cable input. you should be able to get decently long shielded cables for under $20 as they are common. speaker wire for passive speakers if using an amp or receiver you should be able to get for $30-40 a spool or even less depending on quality. most speakers and receivers will use clips or posts for bare wire but its an option on some to use banana plugs (easier to disconnect , reconnect.. if you move the speakers to clean, etc). hdmi cables or optical cables (if you use a receiver) can be had for under $20 but some longer length models might be under $50.
generally i'd say you could get off as cheap as $5 up to around $50 or more depending on what you need to buy. it depends on what you need and how much of it.
9. is it self powered (does it have its own ac plug)? if it does, you could hook it up relatively easily. if it does not , it needs an amp to power it so likely you will not use it (since you would need to buy an amplifier for it on top of your other components).
we can not tell how good it sounds from the specs.
85w rms is a fairly small subwoofer. output will be around the same as some larger pc 5.1 subs like the z506 or similar.
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how to computer 5.1 systems fit into this all?
sets like the z506 or z906 are generally "acceptable". low end budget home theater 5.1 (Monoprice 10565/ energy 5.1 classic sets and their equivalent) will be better overall but for reasonably priced those pc sets sound okay if you need 5.1.
going with higher quality speakers of course will sound better. a pair of klipsch bookshelves for example might not have 5.1 but will sound more powerful and detailed.
whether or not you care or can hear the difference depends on your ears and preferences honestly. i personally dont like going back to worse speakers after having my setup as it feels like all audio is lacking in comparision.
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tldr:
okay, that was alot of information but what does it all mean and what should i buy?
depends on your preferences and needs. honestly it seems like you still dont know what you want so how can we know if you dont?