Normally I dig deep into numbers and the technical side of things, but when it comes to audio i just listen and only worry about how much power it takes to run whatever headphones are in question… What I can tell you is what I have heard when listening to the sound demo’s for each of those headphones.
The SV021 definitely had the more powerful bass out of the two, I didn’t really hear distortion but that could have been connected to the tracks I was listening to at the time, I only spent about 20 minutes with them. The Rhode NTH-100 is more for mastering, but unlike most ‘mastering’ headphones, it is not painful to listen to, and is still fairly even in it’s presentation, but can still put out bass quite well too.
I suggest you take advantage of Amazon and order the SV021 and test them out. If you don’t like them, you have 30 days from whenever they arrive at your house to file a no-fuss return. Amazon will pay for your shipping both ways, and you get your money back if you don’t like them. If you have enough to splash at the NTH-100’s at the same time, then get both and compare them side-by-side. And return whichever one you don’t need.
My bassy headphones are the E-Mu Teaks. I’m not a basshead by any means, but I wanted a reasonably priced headphone with powerful, authoritative, boosted bass that didn’t swamp the mids or reduce overall resolution and performance to give it to me. The Teaks do all of that and they do it very well.
I also recently had the chance to listen to the Meze 99 Noir from massdrop. That had decent bass, and it goes on sale fairly often lately. Currently it is 179 on drop. They don’t have bluetooth though.
Also, there are always ModHouse Argon’s. They are what I personally use, truly exceptional headphones, Zeos pulls these out for review purposes a lot, they are not cheap, and take a powerful amp to drive properly, but if you put Argon’s together a capable system, they rival headphones that run into the thousands of dollars. Here’s a post where I go into detail about them.
My personal system right now is the RME ADI-2 DAC, the Topping A90D, and the Argon MK3 and Argon T60RP (yes I have both, and use both regularly), I also occasionally will buy and listen to other headphones, like the Meze 99 Noir I mentioned earlier, I picked that up as a christmas gift for a family member and tested them out, they are decent too, not as good as Argons, but a lot less expensive.
