Yes I had a Dragon Fly Red - I used it with a laptop when I was away with work. I used it With Mrspeakers Alpha Prime and enjoyed the synergy between them. Like you, ultimately I thought is didn't have the guts to properly drive my headphones at the time (Primes are Planar and love to eat up power). But for a portable and short term solution it worked very well.
Project Ember was one of the earlier amplifiers I had, and if my memory serves correctly, I think I used a Fiio E17k with it. I loved the Ember - I wish I kept it. Fun, musical, powerful, warm. I didn't tube roll... I was using it with Alpha Primes. But, at the time I lusted for more. So I moved to Bifrost & Lyr 2...then Gungnir & Mjolnir 2 with Amperex Bugle Boy 1960's tubes (still have them in my lounge display cabinet lol). I spent a fortune chasing diminishing returns and then work circumstances changed and I sold the lot. I'm now on a new head-fi journey again but will keep it much more sensible.
I did have Philips Fidelio X3 for a short while, but I returned them first and foremost because of QC issues - the headband leather started peeling from the central seam. The other reason was the (to me) dry / thin / analytical sound that contrasted heavily with my X2HR. I was really disappointed in the X3.
D2000 is much more my style. Warmer, lovely lower frequencies, decent soundstage, and a hell of a lot of fun. The Project Polaris pisses all over the Fiio K5 Pro and the Zen Dac that I recently had. It's clearly better. It really opens up the D2000 with plenty of power and crucially there is a ton of headroom which helps the headphone perform.
Personally, I prefer the Polaris just with line out from my pc (without a dac) than most of the other dac/amp combinations I've had. The fun is infectious. The bass is gorgeous, there is a lovely warmth to the sound the Polaris provides. There is plenty of detail but it's not analytical and overbearing. I've not had issues with highs causing discomfort.
Sound stage is wide - embarrassingly, it's honestly made me jump a few times with instruments perceived to be so wide that I thought it was a noise out in the rest of the house and I turn to look out of my home office instantly to see nothing is there haha.
There is a tiny bit of noise when no music playing, but bear in mind I'm pulling from a Pc lineout directly into the Polaris. I think the noise will be from my PC internals. It's not a problem and I cannot hear it at all when music is playing even at low volume. When I get a dac this should resolve.
I am looking forward to getting the Schiit Modi 3. I spoke with Frans (Solderdude) and he said that Modi 3, Topping E30, and a Khardas Tone Board, will all sound similar so I should just go for the one with the aesthetics and features/functionality I prefer. So, I decided on the Schiit Modi 3. Frans said it's a good dac so I'm sure it will be fine.
Give this a go when you get your Polaris -
https://music.amazon.co.uk/albums/B...07FFBSBZF&ref=dm_sh_cc78-8fff-e624-be5d-d6547