Sub or Amp

Ok, wasn't sure where to ask this since it covers two areas, but since it's sound I'm looking for it ended up here.
I have a Kairn pre-amp mated to 2 Klout amps feeding a pair of B&W N802 speakers. My problem is I don't have enough bass.
My question is, should I look to get another Klout amp or a sub? Everyone says the 802's are enough you just need more power. The speakers are bi-wired so I could use one amp for the mid & upper on both speakers & an amp for each speakers lower end.
Or I could get a sub. But if I went this route how do I connect it to this pre-amp? It has no sub outlet?
If you buy a second amp use jumpers on the speakers upper and mids. Then wire the exiting speaker cable to upper (+) and mid (-).

If you get a REL B3 you connect the speaker leads to the power amp. No need to use Preamp.

My vote is to get a sub if you really want to improve bass.
Where do you tie-in to the B&Ws (mid/hi or bass)? Have you replaced the "straps/jumpers" ?
Get a REL or similar sub that takes the signal from the amp output terminals. If you have the amps next to the speakers and they are widely separated it will be a little harder. You could also get a custom adapter made to give 2 line level outputs[Y adaptors] but I am not familiar with the type of connections they use. If they use standard ones it would not be hard. Then you could use any sub. I use REL myself but either will work.
Where do you tie-in to the B&Ws (mid/hi or bass)? Have you replaced the "straps/jumpers" ?

Don't have straps, they have their own set of cables running to uppers & lowers