I bought a used GFA 5500 on Ebay last year. I use it with an Apple Airport Express. No Pre-Amp. I have it driving an old pair of JBL L100s in my basement. It is fantastic! Even though there is no preamp except for the little Airport Express this amp can keep up with me playing my drums. LOUD clean sound that enables me to play "live" without headphones! If you want an amp that has tons of reserve power this is it!

It'll run 4 ohms so I'm thinking of adding my other pair of L100s to see if I can lift the house!