Using a sub with no sub out on my amp


I just bought a Rega IO amplifier it has no sub out I'm using the triangle Berea bro two speakers I'm finding this amp is lacking in bass.  I got about a $250 budget I want to add a subwoofer but I don't have a sub out how do I go about hooking one up to my amplifier any help would be appreciated 
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You are going to need a powered subwoofer. You run your speaker cables into it, set your filter, then run another set of speaker cables out of it and into your speakers.
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 ?
You can also just run leads from the speaker to the sub. It won’t effect your sound unless you are a bat with super hearing. 
Not all subs take this type of connection. Rel is a brand that does. 
Id save more money,250 isnt going to get you anything worth buying .Get a used Rel t5i and run it high level output off your speaker outs
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.