I own a Joule Marianne 300, so I can't speak about Joule amps, although I am very interested in the Rite of passage amps and have read much about the amp, the feedback I have from owners has been nothing less than spectacular for sound quality, build quality has never been an issue anyone has mentioned to me! You would think on private email that would come up if there was a problem.
The 300 preamp is a beautiful unit. I don't think it is as big and impressive looking as say the MBL6010D, which is the other preamp that was in the running when I was preamp shopping! Then again, the 6010 is nearly twice the price. After plugging the 300 in and listening to it, it was obvious the money went into the parts, and that in the end is just where I want it. A while back I purchased a Nagra PLL pre...........my first tube pre. I hated the looks of it, but the sound was undeniable, so I bought it and loved it, the sound quality of the 300 is that much better than the Nagra, and I do feel the built quality "under the hood" is as good as it gets.
Another thing that impresses me with Joule is, when I phone them, you don't get a phone message, or a receptionist who can't get ahold of anyone, or have to leave a message and they'll "get back to you". When you call, Simon answers the phone, and he seems to work 24/7. He has a wealth of audio knowledge, and I trust his audio integrity. I am very happy with my Joule product, would and probably will buy again.
On the other hand, my current amps are the Levinson 33H mono's, which I also love, and are the reference amps in many many systems. However, if you started a thread looking for issues with them, I'm sure you would find lots of people who would step up to the plate and blast them. That being said, if anyone wants to trade their Rite of passage for my Levinsons, drop me an email.