I'm looking to replace my dead desktop PC speakers with a cheap bookshelf setup. I'm looking at cheap bookshelves new, and either a budget amp or something second hand. The main use will be gaming and occasionally background music, so I don't blindingly good quality or particularly loud sound - but I want to be able to appreciate it still. I'd also like to keep the door open to adding a cheap £100 sub at some point. I've heard some good things about the SMSL amps on Amazon - how much do I need to spend to get something that'll run something like a pair of Monitor 50's or Q3020's and put out a reasonably good quality sound, whilst still having the option to connect a sub? Is something like this SMSL AD13 any good? Or should I look at something bigger like a CA Topaz AM1? The other option I've got is looking at actives - Presonus Eris 4.5's have crossed my radar. But I don't know if I can add a sub later (I'm still fairly new to this all.) Can anyone explain to me the benefits of actives in this scenario? I'm happy buying second hand but there is so much out there that I don't feel I can tell the good from the bad.