Not wishing to replace my KEF R100 but in think the addition of a small sub will just give them a greater presence. I have no previous knowledge so am wondering where to start. I presume there is no need for it also to be a KEF? What models to look at? Must be discrete so ideally a model that can hide in a corner or tucked beside a sofa. Amp is Audiolab 6000A and the system is used for music only, Only wishing to spend a couple of hundred pounds so happy to look at used or end of line models. Any advice gratefully received. Thank you.