Bit more on modded T50RP vs modded HP-1.
The Yamaha midrange is just so addictive and good. It's not as extended top or bottom, but the mids are so yummy (my second favorite mids in a headphone, and I am ranking them over the K1000).
Tonally the T50RP is a bit strange. Playing back piano pieces, the tone sounds off. That's the best way I can describe it, like everything sounds a half octave or octave off. Piano is it's biggest pitfall and interestingly this doesn't manifest itself so much on other instruments though it's still there.
Both are great rock headphones, but like my favorite SR-007, the Yamaha has more finesse over the Fosty