First, I have to say, you have an extremely generous friend with good taste in gear. Regarding an amp, if you are really on a tight budget, you might want to consider getting a Parasound Zamp v3 to drive the LS50s. At 45 wpc into 8 ohms, should be more than enough power for a desktop system in a small room played a sane levels. You can also upgrade in the future if you need more power by getting a second Zamp and run in a dual mono configuration which will give you 90 wpc into 8 ohms. It's a nice little amp that can often be found used for under $300. Save up for a good sub and you'll have a great first system.