Pioneer s1 ex dilemma

I really want to get the best out of the speakers without breaking the bank (max £700 for used equipment) but do I go down the road of mono blocks, power amp or something different.
many thanks in advance :)

If your going try to get the best out of them, you will require an upgrade in amplification. Efficiency is good, but with low impedance from the upper base to mid range combined with some notable phase values won't allow them to shine unless you provide them with something that can reach 4 ohms without any stress.

With that said, they measured quite well and if your enjoy a more forward sound, it should end up working quite well for you.

Golly, they are expensive. Stereophile likes them. Your source and amp aren't really up to the job, I guess. You already know that though.