ProLogue Premium Integrated Amps can sometimes cause speakers with built-in powered subwoofers to "flutter".
This is a result of the electrical design of the ProLogue Premium combined with the electrical design of the speakers. A couple of brands of such speakers are Golden Ear or Martin Logan. The fix is simple and free. Using the ProLogue Premium with such speakers can create a remarkably impressive sound, so we wish to encourage the combination.
The fix is to simply use an 82 ohm wirewound resistor right across the speaker taps you are using on the ProLogue Premium Integrated. One end of the resistor goes to negative, the other to the same terminal the speaker is attached to (usually the 4 ohm)..
This is the part as found on Mouser: http://www.mouser.com/ProductDetail/Ohmite/TUW15J82RE/
588-TUW15J82RE
MFG Part No:TUW15J82RE
TUW15J82RE
Ohmite Wirewound Resistors - Through Hole
US HTS:8533310000 ECCN:EAR99 COO:CN
PrimaLuna stocks these resistors and they are available at no charge.