Where to buy a good quality wall wart

I've always had great luck with Digikey.

http://www.digikey.com/

Jameco.com is another one

Not much difference in them,shop for value.

If you want to go high end you might try the Russ Andrews site in the UK. They've just made a replacement wall wart for Cambridge DAC Magic that's amazing.

http://www.russandrews.com/category.asp?lookup=1®ion=UK¤cy=GBP&customer_id=PAA0402047710917FQRUDXZKVLUJCODS&cat_id=PMAINPOWESUP

I got a "Little Pinkie" power supply for my V-DAC, they make ones for other Musical Fidelity units as well. Big improvement, cost around $200. Located in Scotland, don't have address off the top of my head, make it for US voltage on request. You would have to hear it to believe how good it sounds.

Here is the address: http://www.rock-grotto.co.uk/pinkiepsu.htm

Look at companies that provide hospital grade electrical equipment. The requirements hospital's have are pretty tough. I have some hospital grade isolation boxes and they are great, with a low noise floor.

If you want to follow Tpreaves advice and go for value it might be worth a little scrounging at your local Goodwill store. Mine has an entire sheet of pegboard covered with orphaned power supplies, mostly from laptops. I've almost always been able to find a well-built one with the right output. It's easy to swap out the connector for one from Radio Shack if the original one on the wall wart doesn't work.