Probably not the best idea to be honest, but without knowing the specs of the speakers it's not possible to be 100% certain. The key to this is the speaker impedance and whether the Denton(?) amp is rated to handle them.
Do you mean Denton or Denon?
All-in-One kits tend to use speakers rated at 3-4 Ohms each. That's bad news for amps such as Denons. For a start, the speakers aren't expecting to sort of higher voltage levels that 8 Ohm rated amps can generate. This is much higher than the LG main unit could do.
Second, those little LG speakers will suck way more current than 8 Ohm rated speakers would do, and this will make the Denon run hotter than it really should just for ordinary listening.
These power issues though might not be your biggest concern. If you keep the volume low then you can avoid blowing up the amp, or the speakers, or both! But really, where's the fun in that? Do you want to be constantly worried that your new amp might die if you're a bit too enthusiastic with the volume dial, or the music has a bass drop??
No; actually the bigger problem is simply where bass is to come from.
You haven't said which model of LG kit it was. Maybe you're one of the few people who bought a version with tower speakers, which means they might have half a go at doing a little mid-bass; perhaps enough that you could scrape by without a sub if you're not too picky about the sound.
Or you could be in the same camp as 95% of all-in-one kit purchasers where the satellite speakers are really small and the sub is doing bass and most of the midrange too. If that's you then it's not good news I am afraid. The little satellite speakers on their own will sound quite thin and lacking in mid-range. The bass will be non-existent. These aren't designed to run without a sub, and the whole speaker kit is bespoke to its LG main unit. The LG sub is just a low Ohms speaker in a box with a pair of wires. That's not what a Hi-Fi amp is designed to run with. It's all end in tears with a dead amp.
Either ditch the LG speakers or find a s/h main unit of the same model to replace the dead LG.
You're at a crossroads where you could take the path to doing this right. The Denon amp and a pair of decent 6-8 Ohm bookshelf speakers will sound far better than the LG ever could.
