Okay, I am in the market for headphones with a budget of 80 Dollars. The only requirements I have currently is that they are open-back. Right now, I am considering the Sennheiser 518's and the Superlux 668B's. From my knowledge, the Superlux's have a higher impedance, which may be a problem, as I am listening to music through a laptop. The Superlux's are also 30 bucks cheaper, which is nice, and I don't know if the Sennheiser's are worth the extra money in my case. My primary tasks that I use headphones for include listening to music through Spotify and watching YouTube. Which headphones would you recommend for my needs? I am not a basshead, and prefer a more balanced, flat sound. Also, do I need an amp for either of these headphones if I am using my laptops, and will buying high-quality audio files yield better results? Thanks for your guy's help!