I owned these speakers for years. They are great even by today's standards. They are, however, large with two significant woofers and require power. I tried mine with some tube amps in the 80 watt range and the woofers were never adequately supplied. Make sure you get fairly large tube amps if you want to drive these well. I think the Pass Labs is a very good solid state alternative. I do not think you need to spend the money on the 600's. It seems to me that you should have plenty of power with a Pass X250.