Sometimes I wish I knew what I was thinking. This is one of those times. I've had my SE84UFO w/25th mods for about 11 months now and I swapped rectifiers and tube here n there, but it's been awhile. I landed on a good combo and just let it ride. I've had my ZP3 about 8 months and haven't touched the tubes in it for about a month, again liking the combo. I had a Sentinel 5U4G (looks like a rebranded RCA 5U4G) in the UFO and a RCA 5U4G in the ZP3. Few days ago I swapped the rectifiers just to see what change it would make. Wow. It's like someone snuck in and hid a subwoofer in the room. Besides more bass, it sounds quicker and more authoritative. Everything just sounds bigger. Never ceases to amaze me the small changes that can have a huge effect with this gear. Led me to think maybe that Sentinel wasn't up to snuff, so I replaced it with a Westinghouse 5U4G, again looks like a rebranded RCA. That change wasn't as significant. Perhaps one day I'll look back at today and wonder WTF were you thinking?!

Now I'm curious if rolling a rectifier in a power amp has a greater effect as compared to rolling them in a pre like the ZP3?