A few weeks ago I posted asking for views on whehter I would get a significant sonic improvement by having my perfectly well functioning Threshold FET9 preamp refurbished. The consensus was that there would be an audible improvement, so I sent it off to Jon Soderberg for his custom power supply and a complete refurbishment.
I got it back a few days ago and the improvement far exceeds expectations. More transparency, detail and bass. Wow! My system has never sounded this good. I had questioned if the upgrade was worth it, but based on the advice I got I went for it. So this post is to say thanks to those knoweledgable Agoners who helped out and to say if you have an older piece of high quality gear that hasn't been refurbed or upgraded recently it can make a big difference. I was doubtful but not any more.
Thanks again for the help, this is a great online community.