Tower two π speakers sound very nice with tube amps, but they also sound pretty good to me with inexpensive solid state gear, as long as it isn't overdriven and starts clipping. I rather like the system with a little $400.00 Harman Kardon HK3470 receiver - It sounds better than it has a right to.

Give this a try too. Take the tweeter apart and inspect it, removing any dust, lint or debris that you find inside. It's easy to disassemble these tweeters by removing the three screws from the back. It not uncommon to find sawdust accidentally dropped into the mouth during assembly, and then debris is trapped between the diaphragm and the phase plug. So you might check to make sure that your tweeters are clean.