The SHP's have pretty much collected dust while I've owned HD650, Nighthawk, Isine 20, Elear, and done lots of demo's. I recently sold my last pair of cans, Elear, to get a Stax system, and while I'm waiting for the Stax I've been using the SHP's.
In stock form I feel like they have an ok+ soundstage width but zero depth/vertical. Tonality is too bright for me, sounds fake-detailed and grainy, bass is too light. Great sounding for the price you pay, but my spoiled ears could barely enjoy listening to them.
Then I tried putting on some HM5 pads I had laying around (flat velour and angled pleather), and boy what a difference!
First I tried the flat velours, since they were the most similar to the stock pads. The velours brought some soundstage depth and also improved the width ever so slightly. The biggest change was the tonality, they've warmed up and is now quite pleasing to listen to out of a pretty warm amp (Marantz PM5005).
Next I tried the angled pleathers, and I was rather sceptical. Changing both pad material and shape so drastically is usually not a great idea, but I tried anyway:
Holy s**t what happened! These sound so much better now!!
Soundstage is expanded A LOT, both in width and especially in depth. On this point they're not far off, and maybe on par with, the Elear. Tonality is much more to my liking, pretty balanced with a dark tilt. Bass is powerful, mids are a little sucked-out unfortunately, highs are way less strident. They don't sound particularly grainy or "fake-detailed" to me anymore, just really pleasing. Overall, I think these could match my old HD650's (just going from memory). The overall quality (resolution, balance, dynamics etc.) isn't up to the level of the Elear, but the fact that they're 1/10 of the price (including pads) is insane. Comfort has gone up a lot too.