Easy. I'm going to have to go with my main headphone, the Audio Technica ATH-M50. Widely regarded as the budget king of budget headphones (ranked #2 headphone on Head-Fi), and I can vouch that it can compete - easily - with aforementioned B&W P5. It's got a strange tone; it's remotely metallic sounding with a veil of warmth in the sound, while the sound signature itself is V-shaped (extended trebs and lows). It's my go-to headphone for rock, and has so much clarity, soundstage and instrument separation my friend (whose dad has a ridiculously good sound system) was blown away and said it felt like someone was playing the demo track in front of him. I honestly don't know what to say, it's just... Good.