Component Impact

I've been an "audiophile" for 20 years and my experience has taught me that speakers have the most impact on sound. Well that was my experience until one week ago. Over the years I've changed speakers, amps, source, and cables...sometimes I could hear differences and sometimes I couldn't. I recently decided to upgrade my Densen B-250 preamp to the Densen B-250+. My ears still can't believe what I'm hearing...better separation,detail, soundstage. I'm totally shocked by the improvements. Has anyone else experienced significant improvements by changing/upgrading their preamp?