Recommendations for headphones under $400?

Lots of good options at $400 or below, actually. One of my go-to pairs for rock and pop at work is the PSB M4U 1 (which I pair with a dragonfly red). As far as performance for the price it is an excellent choice. Great options at the high end of this price range and with ample bass are the Master & Dynamics MH40 and the OPPO PM-3.

Yes I know there are LOTS of options at this pricepoint, that is part of the problem...lol.
I really do not know a great deal about headphones, by that I mean the names and models that are the best.
Sennheiser I remember having numerous pairs back in the 70,s and 80,s and thinking were excellent value for money at the time.

Sennheiser is still excellent value for the money but IMHO you're not really getting an excellent product until you're up into the 650 range or above. And since your primary criterion was good bass response for rock music, I'm assuming you want to stay away from open backed designs (which the most beloved Sennheisers, including the 650 and especially the 800 are). 

I'd absolutely think about (and preferably try to listen first) to the PSB, M&D, and Oppo options. All are in your price range and offer strong performance.

    uberwaltz,

      If you want good, accurate bass that's able to go as deep as the music demands without sacrificing mid-range and treble performance, I'd suggest either the Oppo PM-3 or Sony MDR-Z7. 
      The Oppo use planar magnetic drivers while the Sony use exceptionally large conventional drivers.  Both are closed back, very comfortable and very good but slightly more than your $400 budget.

Tim