Yup when I bought my MP3 dealer talked to Ralph who said resistor package really not worth the $$$. Dealer owned MP1 which was out of my budget and he didn't have the resistor package in his MP1.
Atma-Sphere Owners, MP-3 Upgrade
So I finally got around to doing the Caddock Resistor Upgrade in my MP-3. I was surprised how everything was just that much better. The Transparency and Soundstage was a decent gain. The sparkle and twinkle of certain instruments was a definite improvement. The Drums was noticeably better. And pianos, sax, and strings were better. Funny thing I didn’t believe in my system I could improve upon things a great deal. Even though each thing was better. And not a huge step forward in each. But when you put it all together. All these little subtleties. All the nicely add details. The presentation. The added depth.... All adds up to a really really nice upgrade. Caddocks are well worth it. I’ve got almost 50 listening hours on them now... I wished I had done this long ago. If you have Atma-Sphere gear. I’d seriously consider the caddocks. I’ve incrementally upgraded UV-1, m60’s, MA-1’s and now my MP-3. Each up grade has added value beyond cost.