Corner Setup

Hi All. So after looking all over the internet to find some help, thought I make an account and ask for your help I am currently setting up an office/living room and since I have always been a video/audio fanatic thought I should put together a home cinema system. However, I have a slight problem....corner sofa! I am attaching a proposed set up I am thinking about giving a shot...the red squares are obviously speakers (I forgot the centre one). What do you think? Any proposals? Also, I haven't bought the sofa yet so if you have any ideas, please share.

Should I go for a 7.1 and include another speaker in the corner just behind the sofa?

Is this what you're proposing? What about equidistance between the sofa and the rear left speaker and the sofa and the rear right speaker? Also, the wardrobe will be couple of inches from the roof (about 3 inches).

I haven't bought the couch and the speaker system yet so i'm pretty flexible. As regards surround system, I was looking at the Onkyo HT-S4505 which seems to have a 'good-enough' specs. Thoughts? 7.1 is definitely a possibility if it provides a better 'solution'.

Also, I have a pair of Pioneer HPM-110. Do you suggest that I use them as the front left/right or should I just stick to the 5.1/7.1 speakers I buy?

Room dimension: 4.27m x 4.03m (the TV wall being the 4.03 m)

Unfortunately I have just finished the ceiling so in-ceiling speakers are not a possibility i'm afraid. I was planning on placing the subwoofer under the TV on the bottom shelf i.e. center front.

Budget is ~ $650 for receiver and speakers (pretty tight I know :/). If I could include my pair of HPM-110 and invest the money saved in a better receiver/subwoofer or something....

Underminded, that's exactly what i had in mind when I was considering 7.1 system! With my tight budget I'll try to go for a 5.1 since 7.1 are more expensive hence I can get a better quality 5.1. However, if I find that a 7.1 beats a 5.1 by far (as regards layout and such) I'll definitely consider the setup you suggested! Thanks!

Flickhtguru, I will consider placing the subwoofer on the floor under the desk then. Shouldn't cause vibrations and such. How does that sound? I will definitely see where it sounds best once I purchase the system. Still doing my research though as regards to which system should I buy.

Here's a redesign now in real scale with your speaker positioning proposals. The only problem is the position of the left surround speaker since it cannot be placed in line with the right surround speaker due to the wardrobe's doors.

so you're saying i move the surround speakers towards the desk. I cannot move the couch because I'm gonna have a chair at the desk. This will result in an angle of less than 90 degrees. Do you think that will have a great effect? Furthermore, is it a big deal if the left and right surround speakers are not at the same level? E.g. the right surround speaker is set on a stand just above the ear while the left surround speaker is placed on one of the shelves on top of the desk.

Thanks again for your reply swampfox!

In case someone has a similar room layout to mine, I managed to come up with a somewhat 'ideal' layout/setup if I may say so thanks to the suggestions above!! Attaching the new layout for reference.