New Dac

What's wrong with your DACMagic? Although the other two are newer they are both less money than your current model was when new and the rPAC is headphone amp as well - so could be a waste of feature for what you want (although I hear it's pretty good).

What exactly are you looking for? (asynchronous USB?), I'd just be cautious if I were you because DACs can be difficult to get big upgrade results from at the best of times (read huge price differences).

I have desktop pc which have coxial out and of course usb so connection is not a problem,

but the dacmagic its simple to small, I feel the rest of the system has more potential, what should I do

Upgrading from a great budget system with a tiny bit of money is very difficult, If you had no DAC it would be easy but you are not lacking anything there. If you had £2000 to spend then there would be lots of things you could do but at this levels it would be tough to make suggestions.

EDIT: Ok I thought of something, how about this:

http://www.ampcity.co.uk/brands/audio-gd/audio-gd-dac-nfb-3.html

The Audio-gd NFB 3.1 is slightly above your price range but could be interesting. It's a Chinese unit with dual wolfson wm8741 DAC chips and 9 selectable digital filters. This could be the best way to mold your system sound to the way you like it, rather than hoping for luck with synergy and personal taste.  

If you order it direct from the company* then you could save a bit of money and also request some new chips: TE8802 (high speed USB - asynchronous), DIR9001 (Low Jitter S/PDIF 24/96 chip) but AmpCity offer a 30 day in home trail so if you can stretch your budget a little this could be perfect for you.

*http://www.audio-gd.com/Pro/dac/NFB3-2011/NFB3.1EN.htm

Anyone else got any ideas? 

Not having heard your kit, I could be completely wrong, but I have to agree with quadpatch. You might get a slightly different sound (which may be to your preference) but I wouldn't expect much of an improvement really. More a sideways step. If you have the opportunity to test out these other DACs with your kit before you buy, then by all means give it a go, but there could be some buyers remorse if you buy without trialling first.