Best LPs to Test Turntables

One LP that brings many stereos to their collective knees very quickly is Paranoid by Black Sabbath. You'll need the original Vertigo English or German white label (not a promo) pressing in good condition. Most stereos simply can't play it at volume- there is a lot of bass energy in the first track.
Verdi Requiem, side one track two, Soria Series on RCA (dowel spine box set). Vast dynamic range!

Thank You Frogman.  The Koln Concerts is always one of my Go To recordings. Second is a box set of Miles' Prestige years with Coltrane

I recommend 78rpm records, though they are not LPs, as the moment of inertia on the tonearm is greatest and the largest amount of information is passed to the cartridge. Recommend Sinatra and the Moderaires, Jo Stafford and some Verdi operas. Good luck with the hunt.

Before you will play any music it's important to check the system with TEST RECORDS if you want to make sure about channel balance, polarity, phase and proper cartridge setup. You can even measure tonearm + cartridge resonance with Hi Fi test LP (free protractor included). Another great LP is Cardas with its unique feature to ultrasonically clean the stylus. What you can do with these 2 LPs you can't do with the music. 

I would go with Stevie Ray Vaughn’s Tin Pan Alley. I’m just starting my own speaker company and this is the track with so much impact that I use this to demo my speaker line.