Voltmeter for Vandersteen 5a setup

More likely you'll need to use this DMM:
https://www.radioshack.com/products/radioshack-true-rms-46-range-digital-multimeter?variant=57170810...

They most likely want to apply low frequency 1V sinewave signal (100Hz -1kHz) and measure/set -3dB point. Any voltmeter will do (no need for true RMS).  One recommended by Czarivey is pretty good one.  I have cheaper, non-RMS version for more almost two decades.  On one occasion I checked it against 6-digit Agilent multimeter and it was accurate within displayed resolution.  

I posted on another thread for you, but just get in touch with Johnny Rutan at Audio Connections in Verona, NJ.  It's near NYC> Not sure where you live, but he's the best set up guy for Vandy's other than Richard and he's more than willing to walk you through. He'll even take your call and help you out.  I noticed you were asking about Ayre and Aesthetics on that other thread. Johnny happens to carry both, however I leaned towards the Ayre as have many of us, but either way you are getting a GREAT amp.  To get a dealer to help you tune your system usually costs a bundle and is well worth it.  If you purchase from Johnny, I promise you that he will take whatever time you need and walk you through the process. It's actually quite simple when you do it his way. He's been setting up Vandersteens for well over 26 years.