Using a sub with no sub out on my amp

So running my speaker cables out of the back of my amp into the sub is not going to change the sound that I'm getting out of my speakers is it going to alter the sound in any way obviously other than adding bass through the sub ?

Thanks guys for the replies I'll look into that suggestion see what I can find one for.  Either that or I just look for another amp.

Thanks for everybody's replies I appreciate it.  First let me say that when I hook up my Cambridge audio axr 85 amp to my speakers there is plenty of bass I'm not a base head so I'm not looking to get crazy amounts of Base but when I hook up my Cambridge to those speakers there is enough I'm satisfied with the bass I just don't like the rest of the sound signature.

I'm not sure if my speakers because why am I getting good bass out of a different amp but when I hook it up to my IO amp I'm not getting as good a base I think it's the amp and I know I'm not going to get really great bass out of a 5 inch woofer.

Those wharfedale diamond 225s I've always wanted those and I heard that those pair very well with my rega IO.  It does have a bigger woofer in The wharf tales and it's not that much bigger of a speaker than mine dimension Wise it's not a whole lot bigger it's a half inch wider 2 in taller I've read a lot of stuff around the internet and on these forums about the wharf deals with my amp 

But I do like to sound signature with my speakers there's just not enough face so I'll probably just add a subwoofer I don't want to sell my speakers get the wharf tales I don't like them.  I'm definitely going to check into your guys recommendations for subwoofers wasn't planning on having to buy one so I really don't have much of a budget for one.

My room is 10 ft x 12 ft so it's not very big and my speakers sit on my desk they're about 5 ft apart I got them on stands so it's not an absolute ideal situation where I can pull them out into the room and put them on floor sanders and probably get how much improve sound with my current room I just don't I can't pull it off they have to go on the desktop.  I will say though they do sound good on the desktop the image well they sound good I got them towed slightly in I'm just missing the low end punch.

Well its kinda a know fact the Wharfdales 225 pair well with Rega IO, at least everywhere i read.

Im going the sub route.

Problem is my small budget of $250.  I want a small footprint also, im guessing 10 inch sub is plenty for my size room.  Looking for suggestion on brands and models in my price range, probally not alot of options, i just dont have anymore budget to go higher.

Those dayton audio look good, has very good reviews on parts Express also great video on how to hook it all up and tune it in excellent thank you.

No i have no choice but to put speakers on desktop on small stands, i just have no room.  My setup is in a bedroom, so very very limited ways to setup, desktop seems to be best.  If i pulled the speakers out off the wall and into the room it would open things up im sure, just dont have the space.