Selecting recordings to do A/B comparisons

I was curious how others selected "professional" recordings to use as an A/B reference track. For example, do you always use a song in the same key as the song you're mixing/mastering? The same genre? Or do you just have a few recordings you use as your standard references?

Dave

www.soundclick.com/steakbone

When I did this, i selected the best song that sounded as close to my song. Genre plays a big part in it and you need to take in account the # of instruments in the pro recording also. i try to come as close to that also. If my song has 2 guitars, one bass and a keyboard and drummer. ill find a band and a song with that also. I havent A/b in a while. Im used to my room now. When i first moved into my new room, i was A/Bing every mix
Cj

Here's a list of recommended references by one mastering engineer. There are several such lists on the 'net. Pick one that's closest to your genre.

I've gone as far as ordering several titles from this list that I was either unfamiliar with or did not own. The good news is that most are older titles and can be purchased used for $3 to $7, so you can build a reference library pretty cheaply.