I've used them before with the POD HD 500 a few years ago . . I had 2 of them and I bought both of them off E bay. They come with different types of speakers, one is FRFR and the other is not. I was not overly impressed with them and got rid of them both eventually. I recently bought a pair of Yamaha DBR 10s and so far I'm quite happy with them. They are not much more than the Tech 21 Power 60s and have, to my ears anyways, way better response. If you can try out different speakers, or whatever before you buy if you can. Also consider what it is you want to do with them ( gig, play at home , jam with friends or something more serious.)
cheers and good luck