I would keep an eye out for Cerwin Vega speakers. Perfect for your budget and style of music.

For what it's worth, starting back in 1972, when I first got the audiophile bug, stereo shop salespeople always told me that folks who loved Heavy Metal, Acid Rock and that sort of music always gravitated toward and nearly always bought JBL speakers. I'm not terribly familiar with Primaluna amps. Regardless, you should make sure that what you buy pairs well with your amp's power & current supply, especially if you are considering speakers considered less than an 8 Ohm nominal load design. Cerwin Vega sounds like a good choice. I also think high efficiency horn design speakers like Ohm would be another good choice. Basically, what this really comes down to is that any well-designed speaker designed to reproduce the signal it's fed as accurately, as possible, would do the job, depending of course on how large your listening room is. I'm assuming, here, that you want something that will play loud (i.e. fill the listening room with sound). If you consider any used speakers with foam surrounds, make sure those surrounds are in good shape and don't or will not need to be replaced anytime soon. Bottom line: LISTEN IN DEMOS AND LET YOUR EARS TELL YOU WHAT YOU LIKE!