More? I'll go deaf haha. I push both till comfortable rather loud listening volume. Been really enjoying the SHP for the last hour or so and then switched back to GSP mid song. The GSP does sound a bit more natural and smooth to me. With the GSP the snare sounds amazing with serious wack where as with the SHP the cymbals are accentuated a more. SHP has more "sparkle" and hiss high up and GSP does the mids especially well and has a slightly warmer signature. A guitar solo on the SHP really tears through the mix very nicely though I must say. I reckon it's definitely down to taste and the music you listen to. To me both sound great it's going to be very interesting to compare with a known entity when I get the 6XX.
Oh. I'd understood you just stuck them in at the same sound setting you usually have for the GSP. Nevermind then.