Moehop,

Hey, I bought the original 170s with the 340c as center and it's an excellent set-up. I haven't heard the 170SEs so can't say how much of a step up but I suspect it's an improvement.

Now, as to an amp. When I bought the system, I was running a Denon 3803 and I recently added an Adcom 7607, a little more power but much better, cleaner power. It was the equivalent of lifting a veil off the 170s. The sound, especially bass in 2 channel, was much better and the mids and highs, already very good, became stronger and more detailed.

So, if I were to make a recommendation, I'd say try the amp route first and see what happens before you go to a 340SE center. Good luck, Dave.