Koa's right in bringing along a single hander for some situations, but I find when I do, it rarely leaves the tube. There's just something about two hand casting that is more rewarding.
The string I use on my Meiser 3/4 switch with is, generally, an Airlfo Scandi from 270 to 300 gr. Don't be fooled by the "3/4" designation. the rod has some spine and would work a summer steelhead just fine.
Re the Echo: A friend let me cast his Echo 5wt last week and it is a great little rod, particularly for the price. (Although the consensus among the casting cogniscenti at the LB Casting Club, was that the recommended line was not ideal for the rod.) I can't remember the grain weight that made it sing, but it was an Airflo Scandi. If interested, I will find out for you.
FFF - CI & THCI
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