Uber expensive repair at United Radio

Another reason to like point to point wiring.
Seems excessive price to pay for replacement for two 16 pin chipsets, can't estimate their troubleshooting time.

If ya are okay with your tech stuck in the 60's, then point to point is fine. Some of use like a bit more modern stuff.

I am more with the OP here than the folks who are saying he is out of line. There are so many instances of companies ripping off folks, simply because they can...that it is almost the norm these days...BUT that in no way excuses the behavior, IMHO. 
While some may say that the OP had an option, because he knew the bid price up front, does that excuse the fact that the bid price was derived by United Radio from knowing that the competition was essentially non existent and as such the OP had very few ( many zero) other options IF he wanted his product repaired...
BUT it is also very clear to me that there are folks on this thread that have severely differing opinions as to what is acceptable business practice..and frankly, ethics. Again, IMHO.

@clearthink I forgot that people in Europe lost their right to complain. It's called hate speech now if you complain about poor service or the price.

I'm not going to blame the guy for going to an authorized service center. If you've invested in a luxury brand, then you want the repair done right the first time. I just think that service centers overcharge repairs for luxury brands because they can. If you can find a decent electronics shop that won't screw you or experiment on your hardware then that's the cheaper route, but like car mechanics, not many honest people in that business. Everyone likes to eat, no one wants to work for free so we embellish our work or labor.

It's called a free market. Places charge what they can get, what the market can bear. Places that charge too much will lose business and those that charge too little will get more. They will then adjust and business volumes will adjust. This assumes that they all do an effective job.

Nobody is getting ripped off here. If a buyer and seller of a product or service agree on a price and both have delivered on what they said they are going to do, then it's a fair deal. If it wasn't they both wouldn't agree to it. If the OP couldn't find anyone to fix his amp for what he considered a reasonable price, he wouldn't do it.