I owned Grand Marquis 160's for a number of years. Loved them. Only sold them as I went to a high sensitivity speaker that required but a few watts. My amps never had a problem. Quality control superb. Reliability superb. I've been following Joule Electra for many years, talking to other owners and reading comments from other owners, their equipment has been more than very reliable. This is well built stuff.
Previous to the Joules, I owned another domestic OTL amp which had so many QC, build, and reliability problems that the best use for that amp would have been for landfill. My experience with the Joule Electras after this disastrous experience was like a breath of fresh air.
In some rooms when monoblocks are used a hum is evident due to a ground loop. The hum does not indicate a problem with the amp. There are tons of variables involved with ground loops including factors that pertain to the other equipment in a system. With but a little work a ground loop induced hum can be eliminated.
Back to Joules the company. I've dealt with lots of audio companies. Joules is one of the best to deal with not only before the sale but after the sale. It is after the sale where many other companies fall short. I would not hesitate to purchase any components from Joule Electra today or in the future.
Some people who responded to this thread expressed shock/surprise to hear of the few issues mentioned within the tread. To my knowledge there's no history outside of his thread of any problems with Joule Electra gear. Whereas many other amp vendors have track records over the years with some to numerous complaints. Joules Electra has a stellar track record and I would not let anything mentioned within this thread cause someone to hesitate exploring the acquisition of a Joule Electra amp or preamp.
Also keep in mind if buying used equipment that not every person takes care of their equipment in the manner that you do. Even a Rolex can have problems if a previous owner did who knows what.