Tish, I know I am going to get absolutely roasted for these comments but here I go... Your nephew has been given a very special gift in your Hafler products. But, he is also 16. As you implied, to him sound quality(most probably) is almost certainly a function of volume and bass output. So, I would recommend a pair of 3 way speakers with 15" woofers. Brands would include Cerwin Vega, Fisher, Infinity, JBL, Kenwood, Klipsch, Panasonic, Pioneer, Sony, etc.(mass fi boom and sizzle speakers). I even have a pair of these, a remnant of my quest for an earbleed days. Interestingly, to 99% of people out there, these are as good as speakers get. Sensitivity should be from 92 to 100+ dB, and they are easy to drive(made for integrateds, receivers, and rack systems[YECHH!]). Yes, the price you gave would be right in the ballpark($100 - $350). And down the road, should his tastes evolve into something more "mature", his Hafler equipment will still serve him in an excellent manner. Good Luck!
Used speakers
I've recently upgraded and am giving my nephew my ancient Hafler 220A amp and Hafler pre-amp. The amp is rated at 120wpc. As befits a 16 year-old, he likes his music loud with lots of bass. I'd like to get him some used speakers in the $250 range. Any suggestions, biggest bang for the buck? Do I need to spend more?