Always best to get new spokes when you get a new rim. Because of the different shapes of the rim, some have curves, some are flat etc, they'll take different length spokes. This counts for hubs too, different flange sizes etc. Give Tarty' a ring, and ask them what spoke length you'd need for the Echo rim, and whatever (T-Pro?) hub. Just don't bodge it by cutting the spokes down, as it'd be a bitch to tru in the future.