Not easy to say, I haven't heard the DT1990's so far. A warm signature means, that the highs are a bit rolled of, so they aren't sharp and the bass is mostly a bit deeper, not extremly present, nothing like Beat's or somethin like that, but still there. A neutral signature is mostly more flat...

The Sundara is also quiet good.

The HD650 is not a neutral and clear headphone, more on the warmer, more intimate side. That also means that they don't have the best soundstage, a K712 for example would be the better choice for gaming, it has a wider soundstage and better imaging.

That's right, but I have to say, that they do a good job on my Hifiman, they're stretched, but they don't tear. The round ones would be the better option, clearly.

The Fostex is good, I wouldn't upgrade the amp now, it would be way better to invest the money in some new cans. You can buy the amp later. I mean, buying somethin' like the LCD2c or even a Hifiman is a good option, maybe the HE560. If you want to spend the money in a better amp an the HD650...

https://www.ebay.com/itm/1-Pair-Velvet-Ear-Pad-Cushion-Replacement-For-Superlux-HD668B-HD669-Headphones/311928218521?hash=item48a05ee399:g:3WQAAOSw20JZfzwE They should fit

Okay, I understand, so,you could buy them on Amazon and if you don't like them, send it back. That's the only way, but I'm not sure if the isolation will be better.

Hey Man, Firstly I want to say that there can be big differences in Sound. The diameter of the HM5 is around 9-10 cm. They should fit, but why do you want to change the original Pads? Comfort is something completely individual, I think both are comfortable.

No, don't get me wrong, I didn't want to recommend you the HD800 or HE500. The Audeze LCD2c is a very good Headphone, you will definitely happy with it. If you really take music serious, then you should step up. As amp, I can only recommend the rHead, but there are a lot of other good amps...

@FastAndClean I also have the HE500, such a ridiculous pair of Headphones, really love them, since I got the HD800, I was thinking very often about selling them, but every time when I pick them and hear some Rock or Jazz, they surprise me again and again.

That's absolutly true, I had a long time ago the HD650, K702, DT990 and DT770, then I bought the HE500. I was really amazed by the Hifiman, so I selled all the other Mid-Fi cans and I was happy for a long long time. Now I also have some other cans to, but I still remind me to the time where I...

Okay, if you want to do so, no Problem. The HE400i is great, but it hasn't the best build quality, the HE4XX is also a great Planar Magnetic. Then you can also think about the HD650 or HD660s. Why Tesla dynamic?, for me the only good Beyer is the T5p, because it's a great closed Headphone, but...

You like the DT1990, the HD660 is a good headphone, but I don't think you will keep both, I had that so often, you think, you buy another one to add it to your main Headphone and be happy. But then the comparison starts and that's the end of satisfaction. That's not useful, you can step up and...

It doesn't really makes sense.