The DAC1 is still one of the top DACs. There aren't very many DACs or headphone amps with flatter frequencies, lower THD+N, or less jitter. Better measurements would be beyond audibility anyway. You might want to buy new to try it, Benchmark has a 30 day return trial.
That said, it's pretty expensive and you can get comparable quality for less. The DAC1 is backed up by extensive measurements though, so if you get one you know the specs aren't lying.
Consider the Cambridge DacMagic, Matrix Quattro, CEntrance DACmini, even the Asus Xonar Essence STX if you use a computer as your source. Personally I think I'll be returning my DAC1 for the Xonar and an Objective2 DIY amp. I had a thread in the Sound Science section asking for DAC recommendations if you want to track it down. These were some of the stars.